CVE-2025-5269

Memory safety bug fixed in Firefox ESR 128.11 and Thunderbird 128.11

View on CVE.org
Published May 27, 2025 CVSS 3.1 · 8.1 High EPSS < 1% KEV · Not listed
Description
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 128.11 and Thunderbird 128.11.

Analysis

AI-generated

Technical impact

A memory safety bug was identified in Firefox ESR 128.10 and Thunderbird 128.10, causing memory corruption that could allow an attacker to execute arbitrary code. The flaw involves unsafe handling of data (CWE-119, CWE-787) and has been fixed in the 128.11 releases.

Affected Systems

The vulnerability affects Mozilla Firefox ESR and Thunderbird versions 128.10. Users running these specific revision numbers are at risk; the problem has been addressed in the subsequent 128.11 updates.

Risk and Exploitability

The CVSS score of 8.1 indicates a high-severity vulnerability, while the EPSS score of less than 1% suggests a very low probability of exploitation in the wild. The flaw is not listed in the CISA KEV catalog. Although the attack vector is not explicitly documented, it can be inferred that malicious web content or email attachments could trigger the vulnerable memory handling, leading to execution of attacker‑chosen code if the conditions are met.

Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

  • Update Firefox ESR to version 128.11 or later, following Mozilla’s official security advisory.
  • Update Thunderbird to version 128.11 or later, following Mozilla’s official security advisory.
  • If immediate update is not possible, restrict or quarantine environments from loading untrusted web pages or email attachments until the patch can be applied.

Generated by OpenCVE AI on April 20, 2026 at 17:05 UTC.

Tracking

Sign in to view the affected projects.

Advisories

Source ID Title
Debian DLA Debian DLA DLA-4191-1 firefox-esr security update
Debian DLA Debian DLA DLA-4194-1 thunderbird security update
Debian DSA Debian DSA DSA-5926-1 firefox-esr security update
Debian DSA Debian DSA DSA-5932-1 thunderbird security update
EUVD EUVD EUVD-2025-18098 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 affects Firefox ESR < 128.11 and Thunderbird < 128.11.
Ubuntu USN Ubuntu USN USN-7663-1 Thunderbird vulnerabilities
History
Type Values Removed Values Added
Description 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 affects 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 128.11 and Thunderbird 128.11.
Type Values Removed Values Added
Title firefox: thunderbird: Memory safety bug Memory safety bug fixed in Firefox ESR 128.11 and Thunderbird 128.11
Type Values Removed Values Added
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N'}

 cvssV3_1

{'score': 8.1, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H'}
Type Values Removed Values Added
First Time appeared Redhat rhel Els
CPEs cpe:/o:redhat:rhel_els:7
Vendors & Products Redhat rhel Els
Type Values Removed Values Added
Description 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 affects Firefox ESR < 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 affects Firefox ESR < 128.11 and Thunderbird < 128.11.
References
Type Values Removed Values Added
First Time appeared Redhat rhel Aus
Redhat rhel Tus
CPEs cpe:/a:redhat:rhel_aus:8.2
cpe:/a:redhat:rhel_aus:8.4
cpe:/a:redhat:rhel_aus:8.6
cpe:/a:redhat:rhel_e4s:8.6
cpe:/a:redhat:rhel_e4s:8.8
cpe:/a:redhat:rhel_e4s:9.2
cpe:/a:redhat:rhel_tus:8.6
cpe:/a:redhat:rhel_tus:8.8
Vendors & Products Redhat rhel Aus
Redhat rhel Tus
Type Values Removed Values Added
First Time appeared Redhat rhel E4s
Redhat rhel Eus
CPEs cpe:/a:redhat:rhel_e4s:9.0
cpe:/a:redhat:rhel_eus:9.4
Vendors & Products Redhat rhel E4s
Redhat rhel Eus
Type Values Removed Values Added
CPEs cpe:/o:redhat:enterprise_linux:10.0
Type Values Removed Values Added
First Time appeared Mozilla
Mozilla firefox
Mozilla thunderbird
CPEs cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*
Vendors & Products Mozilla
Mozilla firefox
Mozilla thunderbird
Type Values Removed Values Added
First Time appeared Redhat
Redhat enterprise Linux
CPEs cpe:/a:redhat:enterprise_linux:8
cpe:/a:redhat:enterprise_linux:9
Vendors & Products Redhat
Redhat enterprise Linux
Type Values Removed Values Added
Title firefox: thunderbird: Memory safety bug
Weaknesses CWE-119
References
Metrics threat_severity

None

 threat_severity

Moderate
Type Values Removed Values Added
Weaknesses CWE-787
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N'}

ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}
Type Values Removed Values Added
Description 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 affects Firefox ESR < 128.11.
References
Earlier changes (9)
Weaknesses
  • CWE-119

    Improper Restriction of Operations within the Bounds of a Memory Buffer

  • CWE-787

    Out-of-bounds Write

Sources

Status
PUBLISHED
Assigner
mozilla
Published
Updated
Apr 13, 2026, 2:29 PM
Reserved
May 27, 2025, 12:29 PM

View source JSON

Updated
Nov 3, 2025, 8:06 PM

JSON

Status
Modified
Published
May 27, 2025, 1:15 PM
Modified
Oct 5, 2026, 3:10 PM

View source JSON

Severity
Moderate
Public date
May 27, 2025, 12:29 PM

View source Bugzilla JSON

Updated
Apr 20, 2026, 5:15 PM

JSON