🛡️ CVE-2025-5268 — firefox

🟠 CVSS 8.1 — High ✅ No Known Exploit CWE-119 NVD
8.1
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

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 code. This vulnerability was fixed in Firefox 139, Firefox ESR 128.11, Thunderbird 139, and Thunderbird 128.11.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is high, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity high, availability high.

Weakness class

CVE-2025-5268 is classified as CWE-119: Improper Restriction of Operations within Memory Buffer Bounds. A read or write is performed without confirming it stays inside the allocated buffer, corrupting adjacent memory.

Affected software

CVE-2025-5268 is recorded against 2 packages.

  • firefox (fixed in 139.0)
  • thunderbird (from 129.0 up to 139.0)

Timeline and source

Published on 27 May 2025 and last revised on 17 June 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

bugzilla.mozilla.org
www.mozilla.org
www.mozilla.org
www.mozilla.org
www.mozilla.org
lists.debian.org
lists.debian.org

CVE-2025-5268 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity HIGH
CVSS Score 8.1
CVSS Vector CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
CWE CWE-119
Public Exploit ✅ No
Source NVD
Published 2025-05-27
Updated 2026-08-11
Modified 2026-06-17
Fix URL N/A

Affected Packages

Software From version Fixed in
firefox — 139.0
thunderbird 129.0 139.0

Similar Threats

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