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OpenAdvisories
High RLSA-2025:10246 5 CVEs

Important: thunderbird security update

Published Jul 29, 2025 · Updated Jul 29, 2025

Summary

Mozilla Thunderbird is a standalone mail and newsgroup client.

Security Fix(es):

* thunderbird: Unsolicited File Download, Disk Space Exhaustion, and Credential Leakage via mailbox:/// Links (CVE-2025-5986)

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 · 8 thunderbird 0:128.12.0-1.el8_10

Vulnerabilities 5

  • Critical 9.8

    Use-after-free in FontFaceSet

    A use-after-free in FontFaceSet resulted in a potentially exploitable crash. This vulnerability was fixed in Firefox 140, Firefox ESR 115.25, Firefox ESR 128.12, Thunderbird 140, and Thunderbird 128.12.

  • Medium 6.5

    Unsolicited File Download, Disk Space Exhaustion, and Credential Leakage via mailbox:/// Links

    A crafted HTML email using mailbox:/// links can trigger automatic, unsolicited downloads of .pdf files to the user's desktop or home directory without prompting, even if auto-saving is disabled. This behavior can be abused to fill the disk with garbage data …

  • Medium 6.5

    Incorrect parsing of URLs could have allowed embedding of youtube.com

    Firefox could have incorrectly parsed a URL and rewritten it to the youtube.com domain when parsing the URL specified in an `embed` tag. This could have bypassed website security checks that restricted which domains users were allowed to embed. This vulnerabi…

  • Medium 6.1

    Content-Disposition header ignored when a file is included in an embed or object tag

    When a file download is specified via the `Content-Disposition` header, that directive would be ignored if the file was included via a `<embed>` or `<object>` tag, potentially making a website vulnerable to a cross-site scripting attack. This vuln…

  • Medium 4.3

    The WebCompat WebExtension shipped with Firefox exposed a persistent UUID

    An attacker who enumerated resources from the WebCompat extension could have obtained a persistent UUID that identified the browser, and persisted between containers and normal/private browsing mode, but not profiles. This vulnerability was fixed in Firefox 1…

References

  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2372281
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2374555
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2374559
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2374561
  • report
    https://bugzilla.redhat.com/show_bug.cgi?id=2374562