CVE-2025-1020 — Out-of-bounds Write in Mozilla Firefox

CWE-787 — Out-of-bounds WriteCWE-120 — Classic Buffer Overflow11 documents8 sources
Severity
9.8CRITICALNVD
EPSS
0.6%
top 30.85%
CISA KEV
Not in KEV
Exploit
No known exploits
Affected products
2
Mozilla FirefoxMozilla Thunderbird
Timeline
PublishedFeb 4
Latest updateFeb 2

Description

Memory safety bugs present in Firefox 134 and Thunderbird 134. 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 135 and Thunderbird 135.

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HExploitability: 3.9 | Impact: 5.9

Affected Packages4 packages

▶NVDmozilla/firefox< 135.0
▶NVDmozilla/thunderbird131.0 — 135.0
▶Ubuntumozilla/firefox< 135.0+build2-0ubuntu0.20.04.1
▶Ubuntumozilla/thunderbird< 1:140.7.1+build1-0ubuntu0.22.04.1

🔴Vulnerability Details

4
OSV
firefox vulnerabilities↗2025-02-11
▶
OSV
CVE-2025-1020: Memory safety bugs present in Firefox 134 and Thunderbird 134↗2025-02-04
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GHSA
GHSA-x7w4-wjh5-78hj: Memory safety bugs present in Firefox 134 and Thunderbird 134↗2025-02-04
▶
CVEList
Memory safety bugs fixed in Firefox 135 and Thunderbird 135↗2025-02-04
▶

📋Vendor Advisories

6
Ubuntu
Thunderbird vulnerabilities↗2026-02-02
▶
Ubuntu
Firefox vulnerabilities↗2025-02-11
▶
Red Hat
firefox: thunderbird: Memory safety bugs fixed in Firefox 135 and Thunderbird 135↗2025-02-04
▶
Debian
CVE-2025-1020: firefox - Memory safety bugs present in Firefox 134 and Thunderbird 134. Some of these bug...↗2025
▶
Mozilla
Mozilla Foundation Security Advisory 2025-11: CVE-2025-1020↗
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CVE-2025-1020 — Out-of-bounds Write in Mozilla Firefox | cvebase