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OpenAdvisories
High RLSA-2026:76761 43 CVEs

Important: firefox security update

Published Oct 24, 2026 · Updated Oct 24, 2026

Summary

Mozilla Firefox is an open-source web browser, designed for standards compliance, performance, and portability.

Security Fix(es):

* firefox: thunderbird: Sandbox escape due to incorrect boundary conditions in the Graphics component (CVE-2026-92035)

* firefox: thunderbird: Use-after-free in the Graphics: Canvas2D component (CVE-2026-100832)

* firefox: Use-after-free in the Layout: Text and Fonts component (CVE-2026-100784)

* firefox: thunderbird: Privilege escalation in the DLL Services component (CVE-2026-100801)

* firefox: thunderbird: Sandbox escape due to incorrect boundary conditions in the Internationalization component (CVE-2026-100794)

* firefox: thunderbird: Privilege escalation in the Address Bar component (CVE-2026-100820)

* firefox: thunderbird: Use-after-free in the Graphics: Canvas2D component (CVE-2026-100777)

* firefox: thunderbird: Information disclosure in the Networking: JAR component (CVE-2026-100766)

* firefox: thunderbird: Use-after-free in the XSLT component (CVE-2026-100779)

* firefox: thunderbird: Privilege escalation in the DOM: Service Workers component (CVE-2026-100807)

* firefox: thunderbird: JIT miscompilation in the JavaScript: WebAssembly component (CVE-2026-100792)

* firefox: Privilege escalation due to use-after-free in the Graphics: WebRender component (CVE-2026-100797)

* firefox: thunderbird: Sandbox escape due to incorrect boundary conditions in the XPCOM component (CVE-2026-100819)

* firefox: thunderbird: Use-after-free in the JavaScript: WebAssembly component (CVE-2026-100776)

* firefox: thunderbird: Use-after-free in the Widget component (CVE-2026-100757)

* firefox: Sandbox escape due to use-after-free in the Graphics component (CVE-2026-100786)

* firefox: thunderbird: Information disclosure in the Networking component (CVE-2026-96869)

* firefox: Sandbox escape due to use-after-free in the DOM: Content Processes component (CVE-2026-100770)

* firefox: thunderbird: Use-after-free in the JavaScript: WebAssembly component (CVE-2026-100769)

* firefox: Use-after-free in the DOM: Core & HTML component (CVE-2026-100791)

* firefox: thunderbird: Sandbox escape due to use-after-free in the Widget: Gtk component (CVE-2026-100818)

* firefox: thunderbird: Privilege escalation due to incorrect boundary conditions in the Graphics component (CVE-2026-100782)

* firefox: firefox: Sandbox escape via use-after-free in DOM component (CVE-2026-100811)

* firefox: thunderbird: Use-after-free in the DOM: Core & HTML component (CVE-2026-100772)

* firefox: thunderbird: Uninitialized memory in the Storage: Quota Manager component (CVE-2026-100759)

* firefox: Sandbox escape due to use-after-free in the DOM: Core & HTML component (CVE-2026-100778)

* firefox: thunderbird: Sandbox escape in the DOM: Navigation component (CVE-2026-100758)

* firefox: thunderbird: Sandbox escape in the Graphics component (CVE-2026-100775)

* firefox: thunderbird: Sandbox escape due to incorrect boundary conditions in the Graphics: WebRender component (CVE-2026-100781)

* firefox: Use-after-free in the DOM: Core & HTML component (CVE-2026-100774)

* firefox: thunderbird: Same-origin policy bypass in the WebExtensions component (CVE-2026-100803)

* firefox: thunderbird: Use-after-free in the Graphics: Canvas2D component (CVE-2026-100789)

* firefox: thunderbird: Use-after-free in the DOM: Core & HTML component (CVE-2026-100785)

* firefox: thunderbird: Site isolation issue in the Panning and Zooming component (CVE-2026-100821)

* firefox: thunderbird: Invalid pointer in the JavaScript: WebAssembly component (CVE-2026-100788)

* firefox: thunderbird: Undefined behavior in the DOM: Streams component (CVE-2026-100771)

* firefox: Sandbox escape due to use-after-free in the DOM: Content Processes component (CVE-2026-100762)

* firefox: thunderbird: Use-after-free in the XSLT component (CVE-2026-100790)

* firefox: thunderbird: Use-after-free in the Storage: IndexedDB component (CVE-2026-100773)

* firefox: thunderbird: Use-after-free in the DOM: Core & HTML component (CVE-2026-100780)

* firefox: thunderbird: Use-after-free in the Networking: Cache component (CVE-2026-100767)

* firefox: thunderbird: Incorrect boundary conditions in the Audio/Video: Playback component (CVE-2026-100756)

* firefox: thunderbird: Uninitialized memory in the Audio/Video component (CVE-2026-100783)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Fixed packages 1

ReleasePackageFixed in
Rocky Linux · 9 firefox 0:140.17.0-1.el9_8

Vulnerabilities 43

  • Critical 9.8

    Invalid pointer in the JavaScript: WebAssembly component

    Invalid pointer in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, and Firefox ESR 140.17.

  • Critical 9.6

    Sandbox escape in the DOM: Navigation component

    Sandbox escape in the DOM: Navigation component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.

  • Critical 9.6

    Sandbox escape due to use-after-free in the DOM: Content Processes component

    Sandbox escape due to use-after-free in the DOM: Content Processes component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.

  • Critical 9.6

    Sandbox escape due to use-after-free in the DOM: Content Processes component

    Sandbox escape due to use-after-free in the DOM: Content Processes component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.

  • Critical 9.6

    Sandbox escape in the Graphics component

    Sandbox escape in the Graphics component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.

  • Critical 9.6

    Sandbox escape due to use-after-free in the DOM: Core & HTML component

    Sandbox escape due to use-after-free in the DOM: Core & HTML component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.

  • Critical 9.6

    Sandbox escape due to incorrect boundary conditions in the Graphics: WebRender component

    Sandbox escape due to incorrect boundary conditions in the Graphics: WebRender component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.

  • Critical 9.6

    Sandbox escape due to use-after-free in the Graphics component

    Sandbox escape due to use-after-free in the Graphics component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.

  • Critical 9.6

    Sandbox escape due to incorrect boundary conditions in the Internationalization component

    Sandbox escape due to incorrect boundary conditions in the Internationalization component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, and Firefox ESR 140.17.

  • Critical 9.6

    Sandbox escape due to use-after-free in the DOM: Core & HTML component

    Sandbox escape due to use-after-free in the DOM: Core & HTML component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, and Firefox ESR 140.17.

  • Critical 9.6

    Sandbox escape due to use-after-free in the Widget: Gtk component

    Sandbox escape due to use-after-free in the Widget: Gtk component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, and Firefox ESR 140.17.

  • Critical 9.6

    Sandbox escape due to incorrect boundary conditions in the XPCOM component

    Sandbox escape due to incorrect boundary conditions in the XPCOM component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.

  • Critical 9.6

    Sandbox escape due to incorrect boundary conditions in the Graphics component

    Sandbox escape due to incorrect boundary conditions in the Graphics component. This vulnerability was fixed in Thunderbird 140.17, Firefox 156, Firefox ESR 153.3, Thunderbird 156, Thunderbird 153.3, Firefox ESR 115.42, and Firefox ESR 140.17.

  • High 8.8

    Use-after-free in the Widget component

    Use-after-free in the Widget component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.

  • High 8.8

    Use-after-free in the Networking: Cache component

    Use-after-free in the Networking: Cache component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.

  • High 8.8

    Use-after-free in the JavaScript: WebAssembly component

    Use-after-free in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, and Firefox ESR 140.17.

  • High 8.8

    Use-after-free in the DOM: Core & HTML component

    Use-after-free in the DOM: Core & HTML component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, and Firefox ESR 140.17.

  • High 8.8

    Use-after-free in the Storage: IndexedDB component

    Use-after-free in the Storage: IndexedDB component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.

  • High 8.8

    Use-after-free in the DOM: Core & HTML component

    Use-after-free in the DOM: Core & HTML component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.

  • High 8.8

    Use-after-free in the JavaScript: WebAssembly component

    Use-after-free in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, and Firefox ESR 140.17.

  • High 8.8

    Use-after-free in the Graphics: Canvas2D component

    Use-after-free in the Graphics: Canvas2D component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.

  • High 8.8

    Use-after-free in the XSLT component

    Use-after-free in the XSLT component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.

  • High 8.8

    Use-after-free in the DOM: Core & HTML component

    Use-after-free in the DOM: Core & HTML component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.

  • High 8.8

    Privilege escalation due to incorrect boundary conditions in the Graphics component

    Privilege escalation due to incorrect boundary conditions in the Graphics component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.

  • High 8.8

    Use-after-free in the Layout: Text and Fonts component

    Use-after-free in the Layout: Text and Fonts component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.

  • High 8.8

    Use-after-free in the DOM: Core & HTML component

    Use-after-free in the DOM: Core & HTML component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.

  • High 8.8

    Use-after-free in the Graphics: Canvas2D component

    Use-after-free in the Graphics: Canvas2D component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.

  • High 8.8

    Use-after-free in the XSLT component

    Use-after-free in the XSLT component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.

  • High 8.8

    Use-after-free in the DOM: Core & HTML component

    Use-after-free in the DOM: Core & HTML component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.

  • High 8.8

    Privilege escalation due to use-after-free in the Graphics: WebRender component

    Privilege escalation due to use-after-free in the Graphics: WebRender component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.

  • High 8.8

    Privilege escalation in the DLL Services component

    Privilege escalation in the DLL Services component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 159, Firefox ESR 153.6, Thunderbird 159, Thunderbird 153.6, Firefox 157, and Firefox ESR 140…

  • High 8.8

    Privilege escalation in the DOM: Service Workers component

    Privilege escalation in the DOM: Service Workers component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, and Firefox ESR 140.17.

  • High 8.8

    Privilege escalation in the Address Bar component

    Privilege escalation in the Address Bar component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, and Firefox ESR 140.17.

  • High 8.8

    Use-after-free in the Graphics: Canvas2D component

    Use-after-free in the Graphics: Canvas2D component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 140.17, Thunderbird 153.4, Firefox ESR 115.42, and Firefox ESR 140.17.

  • High 8.1

    Incorrect boundary conditions in the Audio/Video: Playback component

    Incorrect boundary conditions in the Audio/Video: Playback component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.

  • High 8.1

    Uninitialized memory in the Storage: Quota Manager component

    Uninitialized memory in the Storage: Quota Manager component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.

  • High 8.1

    Undefined behavior in the DOM: Streams component

    Undefined behavior in the DOM: Streams component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.

  • High 8.1

    Same-origin policy bypass in the WebExtensions component

    Same-origin policy bypass in the WebExtensions component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.

  • High 7.1

    JIT miscompilation in the JavaScript: WebAssembly component

    JIT miscompilation in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, and Firefox ESR 140.17.

  • Medium 4.7

    Site isolation issue in the Panning and Zooming component

    Site isolation issue in the Panning and Zooming component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.

  • Medium 4.3

    Information disclosure in the Networking: JAR component

    Information disclosure in the Networking: JAR component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.

  • Medium 4.3

    Uninitialized memory in the Audio/Video component

    Uninitialized memory in the Audio/Video component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.

  • Medium 4.3

    Information disclosure in the Networking component

    Information disclosure in the Networking component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, and Firefox ESR 140.17.

References

  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2533789
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    https://bugzilla.redhat.com/show_bug.cgi?id=2543113
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    https://bugzilla.redhat.com/show_bug.cgi?id=2543114
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    https://bugzilla.redhat.com/show_bug.cgi?id=2543116
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    https://bugzilla.redhat.com/show_bug.cgi?id=2543120
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2543121
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2543123
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2543125
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2543128
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    https://bugzilla.redhat.com/show_bug.cgi?id=2543130
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2543131
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    https://bugzilla.redhat.com/show_bug.cgi?id=2543133
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    https://bugzilla.redhat.com/show_bug.cgi?id=2543134
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    https://bugzilla.redhat.com/show_bug.cgi?id=2543137
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    https://bugzilla.redhat.com/show_bug.cgi?id=2543140
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    https://bugzilla.redhat.com/show_bug.cgi?id=2543142
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    https://bugzilla.redhat.com/show_bug.cgi?id=2543144
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    https://bugzilla.redhat.com/show_bug.cgi?id=2543145
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    https://bugzilla.redhat.com/show_bug.cgi?id=2543146
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    https://bugzilla.redhat.com/show_bug.cgi?id=2543149
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    https://bugzilla.redhat.com/show_bug.cgi?id=2543150
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    https://bugzilla.redhat.com/show_bug.cgi?id=2543152
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    https://bugzilla.redhat.com/show_bug.cgi?id=2543154
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    https://bugzilla.redhat.com/show_bug.cgi?id=2543155
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    https://bugzilla.redhat.com/show_bug.cgi?id=2543156
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    https://bugzilla.redhat.com/show_bug.cgi?id=2543157
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    https://bugzilla.redhat.com/show_bug.cgi?id=2543159
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    https://bugzilla.redhat.com/show_bug.cgi?id=2543160
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    https://bugzilla.redhat.com/show_bug.cgi?id=2543161
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    https://bugzilla.redhat.com/show_bug.cgi?id=2543163
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    https://bugzilla.redhat.com/show_bug.cgi?id=2543164
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    https://bugzilla.redhat.com/show_bug.cgi?id=2543166
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    https://bugzilla.redhat.com/show_bug.cgi?id=2543167
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    https://bugzilla.redhat.com/show_bug.cgi?id=2543172
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    https://bugzilla.redhat.com/show_bug.cgi?id=2543174
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    https://bugzilla.redhat.com/show_bug.cgi?id=2543177
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    https://bugzilla.redhat.com/show_bug.cgi?id=2543182
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    https://bugzilla.redhat.com/show_bug.cgi?id=2543183
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    https://bugzilla.redhat.com/show_bug.cgi?id=2543185