Description
Memory safety bugs present in Firefox ESR 140.3, Thunderbird ESR 140.3, Firefox 143 and Thunderbird 143. 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 code. This vulnerability was fixed in Firefox 144, Firefox ESR 140.4, Thunderbird 144, and Thunderbird 140.4.
Published: 2025-10-14
Score: 8.8 High
EPSS: < 1% Very Low
KEV: No
Impact: Arbitrary code execution via memory corruption
Action: Immediate patch
AI Analysis

Impact

Memory safety bugs were found in Firefox ESR 140.3, Thunderbird ESR 140.3, Firefox 143 and Thunderbird 143. The bugs caused memory corruption and could, with sufficient effort, allow arbitrary code execution. The issue is a classic buffer overrun vulnerability (CWE-119).

Affected Systems

Mozilla Firefox and Thunderbird. Vulnerable releases are Firefox ESR 140.3, Thunderbird ESR 140.3, Firefox 143 and Thunderbird 143. The vulnerability was fixed in Firefox 144, Firefox ESR 140.4, Thunderbird 144 and Thunderbird ESR 140.4.

Risk and Exploitability

The CVSS score is 8.8, indicating high severity. The EPSS score of less than 1% means that the likelihood of exploitation observed in the wild is currently very low, and the vulnerability is not listed in CISA’s KEV catalog. The exploitation path would likely involve a malicious webpage or content that triggers the buffer overrun, leading to arbitrary code execution at the surface level of the browser or mail client.

Generated by OpenCVE AI on April 20, 2026 at 19:11 UTC.

Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

  • Upgrade to Firefox 144 or ESR 140.4 and Thunderbird 144 or ESR 140.4 as soon as possible.
  • If an immediate upgrade is impossible, disable or restrict access to untrusted content, such as disabling active content plugins, until a patch can be applied.
  • Monitor for suspicious activity related to buffer overrun exploitation, such as unexpected process termination or abnormal network connections, and investigate promptly.

Generated by OpenCVE AI on April 20, 2026 at 19:11 UTC.

Tracking

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Advisories
Source ID Title
Debian DLA Debian DLA DLA-4335-1 firefox-esr security update
Debian DLA Debian DLA DLA-4351-1 thunderbird security update
Debian DSA Debian DSA DSA-6025-1 firefox-esr security update
Debian DSA Debian DSA DSA-6040-1 thunderbird security update
Ubuntu USN Ubuntu USN USN-7991-1 Thunderbird vulnerabilities
History

Mon, 13 Apr 2026 15:00:00 +0000

Type Values Removed Values Added
Description Memory safety bugs present in Firefox ESR 140.3, Thunderbird ESR 140.3, Firefox 143 and Thunderbird 143. 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 code. This vulnerability affects Firefox < 144, Firefox ESR < 140.4, Thunderbird < 144, and Thunderbird < 140.4. Memory safety bugs present in Firefox ESR 140.3, Thunderbird ESR 140.3, Firefox 143 and Thunderbird 143. 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 code. This vulnerability was fixed in Firefox 144, Firefox ESR 140.4, Thunderbird 144, and Thunderbird 140.4.

Mon, 03 Nov 2025 18:30:00 +0000

Type Values Removed Values Added
References

Thu, 30 Oct 2025 16:30:00 +0000

Type Values Removed Values Added
Title thunderbird: firefox: Memory safety bugs fixed in Firefox ESR 140.4, Thunderbird ESR 140.4, Firefox 144 and Thunderbird 144 Memory safety bugs fixed in Firefox ESR 140.4, Thunderbird ESR 140.4, Firefox 144 and Thunderbird 144

Mon, 20 Oct 2025 16:00:00 +0000

Type Values Removed Values Added
First Time appeared Mozilla firefox Esr
Vendors & Products Mozilla firefox Esr

Thu, 16 Oct 2025 13:45:00 +0000

Type Values Removed Values Added
First Time appeared Mozilla
Mozilla firefox
Mozilla thunderbird
CPEs cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:*
cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:-:*:*:*
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:esr:*:*:*
Vendors & Products Mozilla
Mozilla firefox
Mozilla thunderbird

Wed, 15 Oct 2025 14:15:00 +0000

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H'}

 ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

cvssV3_1

{'score': 8.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H'}

Wed, 15 Oct 2025 12:30:00 +0000

Type Values Removed Values Added
Title thunderbird: firefox: Memory safety bugs fixed in Firefox ESR 140.4, Thunderbird ESR 140.4, Firefox 144 and Thunderbird 144
Weaknesses CWE-119
References
Metrics threat_severity

None

 cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H'}

threat_severity

Important

Tue, 14 Oct 2025 13:00:00 +0000

Type Values Removed Values Added
Description Memory safety bugs present in Firefox ESR 140.3, Thunderbird ESR 140.3, Firefox 143 and Thunderbird 143. 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 code. This vulnerability affects Firefox < 144, Firefox ESR < 140.4, Thunderbird < 144, and Thunderbird < 140.4.
References

Subscriptions

Mozilla Firefox Firefox Esr Thunderbird
cve-icon MITRE

Status: PUBLISHED

Assigner: mozilla

Published:

Updated: 2026-04-13T14:29:45.602Z

Reserved: 2025-10-13T19:50:13.277Z

Link: CVE-2025-11715

cve-icon Vulnrichment

Updated: 2025-11-03T17:32:03.369Z

cve-icon NVD

Status : Modified

Published: 2025-10-14T13:15:37.800

Modified: 2026-04-13T15:16:40.547

Link: CVE-2025-11715

cve-icon Redhat

Severity : Important

Publid Date: 2025-10-14T12:27:36Z

Links: CVE-2025-11715 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-04-20T19:15:15Z

Weaknesses