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OpenAdvisories
High ALSA-2025:8756 12 CVEs

Important: thunderbird security update

Published Jun 10, 2025 · Updated Oct 29, 2026

Ecosystem: AlmaLinux

Summary

Mozilla Thunderbird is a standalone mail and newsgroup client.

Security Fix(es):

* thunderbird: JavaScript Execution via Spoofed PDF Attachment and file:/// Link (CVE-2025-3909)
* thunderbird: Sender Spoofing via Malformed From Header in Thunderbird (CVE-2025-3875)
* thunderbird: Unsolicited File Download, Disk Space Exhaustion, and Credential Leakage via mailbox:/// Links (CVE-2025-3877)
* thunderbird: Tracking Links in Attachments Bypassed Remote Content Blocking (CVE-2025-3932)
* firefox: thunderbird: Out-of-bounds access when resolving Promise objects (CVE-2025-4918)
* firefox: thunderbird: Out-of-bounds access when optimizing linear sums (CVE-2025-4919)
* firefox: thunderbird: Clickjacking vulnerability could have led to leaking saved payment card details (CVE-2025-5267)
* firefox: thunderbird: Potential local code execution in ?Copy as cURL? command (CVE-2025-5264)
* firefox: thunderbird: Memory safety bugs (CVE-2025-5268)
* firefox: thunderbird: Script element events leaked cross-origin resource status (CVE-2025-5266)
* firefox: thunderbird: Error handling for script execution was incorrectly isolated from web content (CVE-2025-5263)
* firefox: thunderbird: Memory safety bug (CVE-2025-5269)

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
AlmaLinux · 8 thunderbird 128.11.0-1.el8_10.alma.1

Vulnerabilities 12

  • Critical 9.8
    CVE-2025-4918

    Out-of-bounds access when resolving Promise objects

    An attacker was able to perform an out-of-bounds read or write on a JavaScript `Promise` object. This vulnerability was fixed in Firefox 138.0.4, Firefox ESR 128.10.1, Firefox ESR 115.23.1, Thunderbird 128.10.2, and Thunderbird 138.0.2.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi
  • High 8.8
    CVE-2025-4919

    Out-of-bounds access when optimizing linear sums

    An attacker was able to perform an out-of-bounds read or write on a JavaScript object by confusing array index sizes. This vulnerability was fixed in Firefox 138.0.4, Firefox ESR 128.10.1, Firefox ESR 115.23.1, Thunderbird 128.10.2, and Thunderbird 138.0.2.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi
  • High 8.1
    CVE-2025-3909

    JavaScript Execution via Spoofed PDF Attachment and file:/// Link

    Thunderbird's handling of the X-Mozilla-External-Attachment-URL header can be exploited to execute JavaScript in the file:/// context. By crafting a nested email attachment (message/rfc822) and setting its content type to application/pdf, Thunderbird may inco…

    Mozilla Thunderbird thunderbird thunderbird Debian Ubuntu
  • High 8.1
    CVE-2025-5268

    Memory safety bugs fixed in Firefox 139, Thunderbird 139, Firefox ESR 128.11, and Thunderbird 128.11

    Memory safety bugs present in Firefox 138, Thunderbird 138, Firefox ESR 128.10, and Thunderbird 128.10. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary cod…

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi
  • High 8.1
    CVE-2025-5269

    Memory safety bug fixed in Firefox ESR 128.11 and Thunderbird 128.11

    Memory safety bug present in Firefox ESR 128.10, and Thunderbird 128.10. This bug showed evidence of memory corruption and we presume that with enough effort this could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox ESR 128…

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi
  • High 7.5
    CVE-2025-3875

    Sender Spoofing via Malformed From Header in Thunderbird

    Thunderbird parses addresses in a way that can allow sender spoofing in case the server allows an invalid From address to be used. For example, if the From header contains an (invalid) value "Spoofed Name ", Thunderbird treats spoofed@example.com as the actua…

    Mozilla Thunderbird thunderbird thunderbird Debian Ubuntu
  • Medium 6.5
    CVE-2025-3932

    Tracking Links in Attachments Bypassed Remote Content Blocking

    It was possible to craft an email that showed a tracking link as an attachment. If the user attempted to open the attachment, Thunderbird automatically accessed the link. The configuration to block remote content did not prevent that. Thunderbird has been fix…

    Mozilla Thunderbird thunderbird thunderbird Debian Ubuntu
  • Medium 5.4
    CVE-2025-5267

    Clickjacking vulnerability could have led to leaking saved payment card details

    A clickjacking vulnerability could have been used to trick a user into leaking saved payment card details to a malicious page. This vulnerability was fixed in Firefox 139, Firefox ESR 128.11, Thunderbird 139, and Thunderbird 128.11.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi
  • Medium 4.8
    CVE-2025-5264

    Potential local code execution in “Copy as cURL” command

    Due to insufficient escaping of the newline character in the “Copy as cURL” feature, an attacker could trick a user into using this command, potentially leading to local code execution on the user's system. This vulnerability was fixed in Firefox 139, Firefox…

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi
  • Medium 4.3
    CVE-2025-5263

    Error handling for script execution was incorrectly isolated from web content

    Error handling for script execution was incorrectly isolated from web content, which could have allowed cross-origin leak attacks. This vulnerability was fixed in Firefox 139, Firefox ESR 115.24, Firefox ESR 128.11, Thunderbird 139, and Thunderbird 128.11.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi
  • Medium 4.3
    CVE-2025-5266

    Script element events leaked cross-origin resource status

    Script elements loading cross-origin resources generated load and error events which leaked information enabling XS-Leaks attacks. This vulnerability was fixed in Firefox 139, Firefox ESR 128.11, Thunderbird 139, and Thunderbird 128.11.

    Mozilla Firefox Thunderbird thunderbird Browsers Debian Ubuntu Wolfi
  • Unscored —
    CVE-2025-3877 Rejected

    This CVE was marked as fixed, but due to other code landing - was not actually fixed. It was subsequently fixed in CVE-…

References

  • report
    https://access.redhat.com/security/cve/CVE-2025-3875
  • report
    https://access.redhat.com/security/cve/CVE-2025-3877
  • report
    https://access.redhat.com/security/cve/CVE-2025-3909
  • report
    https://access.redhat.com/security/cve/CVE-2025-3932
  • report
    https://access.redhat.com/security/cve/CVE-2025-4918
  • report
    https://access.redhat.com/security/cve/CVE-2025-4919
  • report
    https://access.redhat.com/security/cve/CVE-2025-5263
  • report
    https://access.redhat.com/security/cve/CVE-2025-5264
  • report
    https://access.redhat.com/security/cve/CVE-2025-5266
  • report
    https://access.redhat.com/security/cve/CVE-2025-5267
  • report
    https://access.redhat.com/security/cve/CVE-2025-5268
  • report
    https://access.redhat.com/security/cve/CVE-2025-5269
  • report
    https://bugzilla.redhat.com/2366283
  • report
    https://bugzilla.redhat.com/2366287
  • report
    https://bugzilla.redhat.com/2366291
  • report
    https://bugzilla.redhat.com/2366297
  • report
    https://bugzilla.redhat.com/2367016
  • report
    https://bugzilla.redhat.com/2367018
  • report
    https://bugzilla.redhat.com/2368750
  • report
    https://bugzilla.redhat.com/2368751
  • report
    https://bugzilla.redhat.com/2368752
  • report
    https://bugzilla.redhat.com/2368755
  • report
    https://bugzilla.redhat.com/2368756
  • report
    https://bugzilla.redhat.com/2368757
  • advisory
    https://errata.almalinux.org/8/ALSA-2025-8756.html