CVE-2026-12329

Memory safety bug fixed in Thunderbird ESR 140.12

View on CVE.org
Published Jun 16, 2026 CVSS 3.1 · 5.3 Medium EPSS < 1% KEV · Not listed
Description
Memory safety bug fixed in Thunderbird ESR 140.12. This vulnerability was fixed in Firefox ESR 140.12 and Thunderbird 140.12.

Analysis

AI-generated

Technical impact

The vulnerability involves a memory safety bug that can result in buffer overflows, use‑after‑free conditions, or null pointer dereferences. This can corrupt application memory, potentially causing crashes or providing a foothold for malicious code if the flaw is successfully leveraged.

Affected Systems

Mozilla Firefox (Extended Support Release) prior to version 140.12 and Mozilla Thunderbird (Extended Support Release) prior to version 140.12 are affected.

Risk and Exploitability

The CVSS score of 5.3 indicates moderate severity. With an EPSS score below 1% and no listing in CISA KEV, exploitation is currently unlikely. Nevertheless, the flaw could be triggered by maliciously crafted email content or attachments, making the vector likely local or remote delivery of corrupted data. Successful exploitation would depend on an attacker’s ability to get the target to process the harmful input.

Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

  • Upgrade Firefox ESR to version 140.12 or later.
  • Upgrade Thunderbird ESR to version 140.12 or later.
  • If an upgrade is not immediately possible, restrict the processing of potentially malformed email attachments and remain vigilant for abnormal crashes.

Generated by OpenCVE AI on June 17, 2026 at 21:40 UTC.

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-4635-1 firefox-esr security update
Debian DLA Debian DLA DLA-4636-1 thunderbird security update
Debian DSA Debian DSA DSA-6350-1 firefox-esr security update
Debian DSA Debian DSA DSA-6351-1 thunderbird security update
References
Link Providers
https://access.redhat.com/errata/RHSA-2026:27717 cve-icon
https://access.redhat.com/errata/RHSA-2026:27733 cve-icon
https://access.redhat.com/errata/RHSA-2026:27734 cve-icon
https://access.redhat.com/errata/RHSA-2026:29940 cve-icon
https://access.redhat.com/errata/RHSA-2026:30846 cve-icon
https://access.redhat.com/errata/RHSA-2026:33445 cve-icon
https://access.redhat.com/errata/RHSA-2026:36100 cve-icon
https://access.redhat.com/errata/RHSA-2026:36101 cve-icon
https://access.redhat.com/errata/RHSA-2026:36102 cve-icon
https://access.redhat.com/errata/RHSA-2026:36103 cve-icon
https://access.redhat.com/errata/RHSA-2026:37210 cve-icon
https://access.redhat.com/errata/RHSA-2026:37391 cve-icon
https://access.redhat.com/errata/RHSA-2026:38506 cve-icon
https://access.redhat.com/errata/RHSA-2026:38750 cve-icon
https://access.redhat.com/errata/RHSA-2026:38751 cve-icon
https://access.redhat.com/errata/RHSA-2026:38753 cve-icon
https://access.redhat.com/errata/RHSA-2026:39011 cve-icon
https://access.redhat.com/errata/RHSA-2026:39141 cve-icon
https://access.redhat.com/errata/RHSA-2026:39142 cve-icon
https://access.redhat.com/errata/RHSA-2026:39428 cve-icon
https://access.redhat.com/errata/RHSA-2026:39706 cve-icon
https://access.redhat.com/security/cve/CVE-2026-12329 cve-icon
https://bugzilla.mozilla.org/show_bug.cgi?id=2044738 cve-icon cve-icon
https://bugzilla.redhat.com/show_bug.cgi?id=2489214 cve-icon
https://nvd.nist.gov/vuln/detail/CVE-2026-12329 cve-icon
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-12329.json cve-icon
https://www.cve.org/CVERecord?id=CVE-2026-12329 cve-icon
https://www.mozilla.org/security/advisories/mfsa2026-58/ cve-icon cve-icon
https://www.mozilla.org/security/advisories/mfsa2026-58/#CVE-2026-12329 cve-icon
https://www.mozilla.org/security/advisories/mfsa2026-61/ cve-icon cve-icon
https://www.mozilla.org/security/advisories/mfsa2026-61/#CVE-2026-12329 cve-icon
History
Type Values Removed Values Added
First Time appeared Mozilla thunderbird
CPEs cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:esr:*:*:*
Vendors & Products Mozilla thunderbird
Type Values Removed Values Added
Description Memory safety bug fixed in Firefox ESR 140.12. This vulnerability was fixed in Firefox ESR 140.12. Memory safety bug fixed in Thunderbird ESR 140.12. This vulnerability was fixed in Firefox ESR 140.12 and Thunderbird 140.12.
Title Memory safety bug fixed in Firefox ESR 140.12 Memory safety bug fixed in Thunderbird ESR 140.12
References
Type Values Removed Values Added
Weaknesses CWE-119
CWE-416
CWE-476
Metrics cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L'}

ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}
Type Values Removed Values Added
First Time appeared Mozilla
Mozilla firefox
Vendors & Products Mozilla
Mozilla firefox
Type Values Removed Values Added
Description Memory safety bug fixed in Firefox ESR 140.12. This vulnerability was fixed in Firefox ESR 140.12.
Title Memory safety bug fixed in Firefox ESR 140.12
References
Earlier changes (1)
Weaknesses
  • CWE-119

    Improper Restriction of Operations within the Bounds of a Memory Buffer

  • CWE-416

    Use After Free

  • CWE-476

    NULL Pointer Dereference

Sources

Status
PUBLISHED
Assigner
mozilla
Published
Updated
Jul 15, 2026, 11:48 AM
Reserved
Jun 15, 2026, 3:08 PM

View source JSON

Updated
Jul 15, 2026, 11:48 AM

JSON

Status
Modified
Published
Jun 16, 2026, 1:16 PM
Modified
Oct 25, 2026, 11:10 PM

View source JSON

Severity
Important
Public date
Jun 16, 2026, 11:53 AM

View source Bugzilla JSON

Updated
Jun 17, 2026, 9:45 PM

JSON