CVE-2025-5269 — Out-of-bounds Write in Mozilla Firefox

CWE-787 — Out-of-bounds WriteCWE-119 — Improper Restriction of Operations within the Bounds of a Memory Buffer9 documents8 sources
Severity
8.1HIGHNVD
EPSS
0.4%
top 37.51%
CISA KEV
Not in KEV
Exploit
No known exploits
Affected products
2
Mozilla ThunderbirdMozilla Firefox
Timeline
PublishedMay 27
Latest updateJul 22

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.

CVSS vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:HExploitability: 2.2 | Impact: 5.9

Affected Packages3 packages

▶NVDmozilla/firefox< 128.11.0
▶NVDmozilla/thunderbird< 128.11.0
▶Debianmozilla/thunderbird< 1:128.11.0esr-1~deb11u1+3

🔴Vulnerability Details

3
OSV
CVE-2025-5269: Memory safety bug present in Firefox ESR 128↗2025-05-27
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GHSA
GHSA-qjw8-8452-9587: Memory safety bug present in Firefox ESR 128↗2025-05-27
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CVEList
Memory safety bug fixed in Firefox ESR 128.11 and Thunderbird 128.11↗2025-05-27
▶

📋Vendor Advisories

5
Ubuntu
Thunderbird vulnerabilities↗2025-07-22
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Red Hat
firefox: thunderbird: Memory safety bug↗2025-05-27
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Debian
CVE-2025-5269: firefox-esr - Memory safety bug present in Firefox ESR 128.10, and Thunderbird 128.10. This bu...↗2025
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Mozilla
Mozilla Foundation Security Advisory 2025-44: CVE-2025-5269↗
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Mozilla
Mozilla Foundation Security Advisory 2025-46: CVE-2025-5269↗
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CVE-2025-5269 — Out-of-bounds Write in Mozilla Firefox | cvebase