CVE catalog

CVE-2026-8949

Integer overflow in the Widget: Win32 component. This vulnerability was fixed in Firefox 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.

[CVE catalog]

Severity: High · CVSS 7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published: May 19, 2026, 12:00:00 AM UTC
Source: [NVD] · [CVE record]
EPSS: 0.58% · Oct 25, 2026

Integer overflow in the Widget: Win32 component. This vulnerability was fixed in Firefox 151, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.

Vulnerable and fixed packages

Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.

Distribution	Package	Release	Version	Status
Debian	firefox-esr	sid	`153.5.1esr-1`	not affected
Debian	firefox-esr	forky	`153.5.1esr-1`	not affected
Debian	firefox-esr	trixie	`140.15.0esr-1~deb13u1`	not affected
Debian	firefox-esr	trixie-security	`153.5.1esr-1~deb13u1`	not affected
Debian	firefox-esr	bookworm	`140.12.0esr-1~deb12u1`	not affected
Debian	firefox-esr	bookworm-security	`153.5.1esr-1~deb12u1`	not affected
Debian	thunderbird	sid	`1:153.5.1esr-1`	not affected
Debian	thunderbird	forky	`1:153.5.0esr-1`	not affected
Debian	thunderbird	trixie	`1:140.12.0esr-1~deb13u1`	not affected
Debian	thunderbird	trixie-security	`1:153.5.1esr-1~deb13u2`	not affected
Debian	thunderbird	bookworm	`1:140.12.0esr-1~deb12u1`	not affected
Debian	thunderbird	bookworm-security	`1:153.5.1esr-1~deb12u1`	not affected
Cpe	firefox	Not reported	`140.11.0`	fixed
Cpe	firefox	Not reported	`151.0.0`	fixed
Cpe	thunderbird	Not reported	`140.11`	fixed
Cpe	thunderbird	Not reported	`151.0.0`	fixed
Cpe	firefox-esr	Not reported	Not reported	not affected
Cpe	thunderbird	Not reported	Not reported	not affected
Cpe	firefox	Not reported	`151.0.0`	fixed
Cpe	thunderbird	Not reported	`151.0.0`	fixed
Ubuntu	mozjs52	18.04	`52.3.1-0ubuntu3`	vulnerable
Ubuntu	mozjs52	18.04	`52.3.1-7fakesync1`	vulnerable
Ubuntu	mozjs52	18.04	`52.8.1-0ubuntu0.18.04.1`	vulnerable
Ubuntu	mozjs52	18.04	`52.9.1-0ubuntu0.18.04.1`	vulnerable
Ubuntu	mozjs38	18.04	`38.8.0~repack1-0ubuntu1`	vulnerable
Ubuntu	mozjs38	18.04	`38.8.0~repack1-0ubuntu3`	vulnerable
Ubuntu	mozjs38	18.04	`38.8.0~repack1-0ubuntu4`	vulnerable
Ubuntu	mozjs68	20.04	`68.5.0-1~fakesync`	vulnerable
Ubuntu	mozjs68	20.04	`68.5.0-2~fakesync`	vulnerable
Ubuntu	mozjs68	20.04	`68.6.0-1`	vulnerable
Ubuntu	mozjs68	20.04	`68.6.0-1ubuntu1`	vulnerable
Ubuntu	mozjs52	20.04	`52.9.1-1build1`	vulnerable
Ubuntu	mozjs52	20.04	`52.9.1-1ubuntu3`	vulnerable
Ubuntu	mozjs102	22.04	`102.11.0-0ubuntu0.22.04.1`	vulnerable
Ubuntu	mozjs102	22.04	`102.12.0-0ubuntu0.22.04.1`	vulnerable
Ubuntu	mozjs102	22.04	`102.13.0-0ubuntu0.22.04.1`	vulnerable
Ubuntu	mozjs102	22.04	`102.15.1-0ubuntu0.22.04.1`	vulnerable
Ubuntu	mozjs78	22.04	`78.13.0-1`	vulnerable
Ubuntu	mozjs78	22.04	`78.15.0-2`	vulnerable
Ubuntu	mozjs78	22.04	`78.15.0-4ubuntu1`	vulnerable
Ubuntu	mozjs91	22.04	`91.5.1-0ubuntu1`	vulnerable
Ubuntu	mozjs91	22.04	`91.6.0-1`	vulnerable
Ubuntu	mozjs91	22.04	`91.6.0-2`	vulnerable
Ubuntu	mozjs91	22.04	`91.7.0-2`	vulnerable
Ubuntu	mozjs91	22.04	`91.10.0-0ubuntu1`	vulnerable
Ubuntu	thunderbird	22.04	`1:91.1.2+build1-0ubuntu1`	vulnerable
Ubuntu	thunderbird	22.04	`1:91.3.0+build2-0ubuntu1`	vulnerable
Ubuntu	thunderbird	22.04	`1:91.3.1+build1-0ubuntu1`	vulnerable
Ubuntu	thunderbird	22.04	`1:91.3.2+build1-0ubuntu1`	vulnerable
Ubuntu	thunderbird	22.04	`1:91.4.0+build1.1-0ubuntu1`	vulnerable
Ubuntu	thunderbird	22.04	`1:91.4.0+build2-0ubuntu1`	vulnerable
Ubuntu	thunderbird	22.04	`1:91.5.0+build1-0ubuntu1`	vulnerable
Ubuntu	thunderbird	22.04	`1:91.5.1+build1-0ubuntu1`	vulnerable
Ubuntu	thunderbird	22.04	`1:91.6.1+build1-0ubuntu1`	vulnerable
Ubuntu	thunderbird	22.04	`1:91.7.0+build1-0ubuntu1`	vulnerable
Ubuntu	thunderbird	22.04	`1:91.7.0+build2-0ubuntu1`	vulnerable
Ubuntu	thunderbird	22.04	`1:91.8.0+build2-0ubuntu1`	vulnerable
Ubuntu	thunderbird	22.04	`1:91.9.1+build1-0ubuntu0.22.04.1`	vulnerable
Ubuntu	thunderbird	22.04	`1:91.11.0+build2-0ubuntu0.22.04.1`	vulnerable
Ubuntu	thunderbird	22.04	`1:102.2.2+build1-0ubuntu0.22.04.1`	vulnerable
Ubuntu	thunderbird	22.04	`1:102.4.2+build2-0ubuntu0.22.04.1`	vulnerable
Ubuntu	thunderbird	22.04	`1:102.7.1+build2-0ubuntu0.22.04.1`	vulnerable
Ubuntu	thunderbird	22.04	`1:102.8.0+build2-0ubuntu0.22.04.1`	vulnerable
Ubuntu	thunderbird	22.04	`1:102.9.0+build1-0ubuntu0.22.04.1`	vulnerable
Ubuntu	thunderbird	22.04	`1:102.10.0+build2-0ubuntu0.22.04.1`	vulnerable
Ubuntu	thunderbird	22.04	`1:102.11.0+build1-0ubuntu0.22.04.1`	vulnerable
Ubuntu	thunderbird	22.04	`1:102.13.0+build1-0ubuntu0.22.04.1`	vulnerable
Ubuntu	thunderbird	22.04	`1:102.15.0+build1-0ubuntu0.22.04.1`	vulnerable
Ubuntu	thunderbird	22.04	`1:102.15.1+build1-0ubuntu0.22.04.1`	vulnerable
Ubuntu	thunderbird	22.04	`1:115.3.1+build1-0ubuntu0.22.04.2`	vulnerable
Ubuntu	thunderbird	22.04	`1:115.4.1+build1-0ubuntu0.22.04.1`	vulnerable
Ubuntu	thunderbird	22.04	`1:115.5.0+build1-0ubuntu0.22.04.1`	vulnerable
Ubuntu	thunderbird	22.04	`1:115.6.0+build2-0ubuntu0.22.04.1`	vulnerable
Ubuntu	thunderbird	22.04	`1:115.8.1+build1-0ubuntu0.22.04.1`	vulnerable
Ubuntu	thunderbird	22.04	`1:115.9.0+build1-0ubuntu0.22.04.1`	vulnerable
Ubuntu	thunderbird	22.04	`1:115.10.1+build1-0ubuntu0.22.04.1`	vulnerable
Ubuntu	thunderbird	22.04	`1:115.11.0+build2-0ubuntu0.22.04.1`	vulnerable
Ubuntu	thunderbird	22.04	`1:115.12.0+build3-0ubuntu0.22.04.1`	vulnerable
Ubuntu	thunderbird	22.04	`1:115.13.0+build5-0ubuntu0.22.04.1`	vulnerable
Ubuntu	thunderbird	22.04	`1:115.15.0+build1-0ubuntu0.22.04.1`	vulnerable
Ubuntu	thunderbird	22.04	`1:115.16.0+build2-0ubuntu0.22.04.1`	vulnerable
Ubuntu	thunderbird	22.04	`1:115.18.0+build1-0ubuntu0.22.04.1`	vulnerable
Ubuntu	thunderbird	22.04	`1:128.12.0+build1-0ubuntu0.22.04.1`	vulnerable
Ubuntu	thunderbird	22.04	`1:140.7.1+build1-0ubuntu0.22.04.1`	vulnerable
Ubuntu	mozjs102	24.04	`102.15.1-1`	vulnerable
Ubuntu	mozjs102	24.04	`102.15.1-3ubuntu2`	vulnerable
Ubuntu	mozjs115	24.04	`115.3.0-0ubuntu1`	vulnerable
Ubuntu	mozjs115	24.04	`115.4.0-2`	vulnerable
Ubuntu	mozjs115	24.04	`115.5.0-1`	vulnerable
Ubuntu	mozjs115	24.04	`115.6.0-1`	vulnerable
Ubuntu	mozjs115	24.04	`115.7.0-4`	vulnerable
Ubuntu	mozjs115	24.04	`115.8.0-1`	vulnerable
Ubuntu	mozjs115	24.04	`115.9.0-1`	vulnerable
Ubuntu	mozjs115	24.04	`115.9.0-1build1`	vulnerable
Ubuntu	mozjs115	24.04	`115.10.0-1`	vulnerable

Fixed-version evidence

Distribution	Package	Type	Release	Fixed version	Urgency	Origin	Bugs
Debian	firefox-esr	source	sid	`Not affected`	unimportant	Not reported	Not reported
Debian	firefox-esr	source	forky	`Not affected`	unimportant	Not reported	Not reported
Debian	firefox-esr	source	trixie	`Not affected`	unimportant	Not reported	Not reported
Debian	firefox-esr	source	bookworm	`Not affected`	unimportant	Not reported	Not reported
Debian	thunderbird	source	sid	`Not affected`	unimportant	Not reported	Not reported
Debian	thunderbird	source	forky	`Not affected`	unimportant	Not reported	Not reported
Debian	thunderbird	source	trixie	`Not affected`	unimportant	Not reported	Not reported
Debian	thunderbird	source	bookworm	`Not affected`	unimportant	Not reported	Not reported
Cpe	firefox	cpe	Not reported	`140.11.0`	Not reported	Not reported	Not reported
Cpe	firefox	cpe	Not reported	`151.0.0`	Not reported	Not reported	Not reported
Cpe	thunderbird	cpe	Not reported	`140.11`	Not reported	Not reported	Not reported
Cpe	thunderbird	cpe	Not reported	`151.0.0`	Not reported	Not reported	Not reported
Cpe	firefox	cpe	Not reported	`151.0.0`	Not reported	NVD-CVE-2026-8949	Not reported
Cpe	thunderbird	cpe	Not reported	`151.0.0`	Not reported	NVD-CVE-2026-8949	Not reported

OpenFactory catalog packages

[Debian 12 (Bookworm)]

[firefox-esr]Not affected
Details (4)
- 140.12.0esr-1~deb12u1 · amd64 · bookworm
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.12.0esr-1~deb12u1 · arm64 · bookworm
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.14.0esr-1~deb12u1 · amd64 · bookworm-security
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.14.0esr-1~deb12u1 · arm64 · bookworm-security
  Not affected
  nvd · firefox-esr · debian · bookworm
[firefox-esr-l10n-ach]Not affected
Source package: [firefox-esr]
Details (4)
- 140.12.0esr-1~deb12u1 · all · bookworm
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.12.0esr-1~deb12u1 · all · bookworm
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.14.0esr-1~deb12u1 · all · bookworm-security
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.14.0esr-1~deb12u1 · all · bookworm-security
  Not affected
  nvd · firefox-esr · debian · bookworm
[firefox-esr-l10n-af]Not affected
Source package: [firefox-esr]
Details (4)
- 140.12.0esr-1~deb12u1 · all · bookworm
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.12.0esr-1~deb12u1 · all · bookworm
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.14.0esr-1~deb12u1 · all · bookworm-security
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.14.0esr-1~deb12u1 · all · bookworm-security
  Not affected
  nvd · firefox-esr · debian · bookworm
[firefox-esr-l10n-all]Not affected
Source package: [firefox-esr]
Details (4)
- 140.12.0esr-1~deb12u1 · all · bookworm
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.12.0esr-1~deb12u1 · all · bookworm
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.14.0esr-1~deb12u1 · all · bookworm-security
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.14.0esr-1~deb12u1 · all · bookworm-security
  Not affected
  nvd · firefox-esr · debian · bookworm
[firefox-esr-l10n-an]Not affected
Source package: [firefox-esr]
Details (4)
- 140.12.0esr-1~deb12u1 · all · bookworm
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.12.0esr-1~deb12u1 · all · bookworm
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.14.0esr-1~deb12u1 · all · bookworm-security
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.14.0esr-1~deb12u1 · all · bookworm-security
  Not affected
  nvd · firefox-esr · debian · bookworm
[firefox-esr-l10n-ar]Not affected
Source package: [firefox-esr]
Details (4)
- 140.12.0esr-1~deb12u1 · all · bookworm
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.12.0esr-1~deb12u1 · all · bookworm
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.14.0esr-1~deb12u1 · all · bookworm-security
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.14.0esr-1~deb12u1 · all · bookworm-security
  Not affected
  nvd · firefox-esr · debian · bookworm
[firefox-esr-l10n-ast]Not affected
Source package: [firefox-esr]
Details (4)
- 140.12.0esr-1~deb12u1 · all · bookworm
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.12.0esr-1~deb12u1 · all · bookworm
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.14.0esr-1~deb12u1 · all · bookworm-security
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.14.0esr-1~deb12u1 · all · bookworm-security
  Not affected
  nvd · firefox-esr · debian · bookworm
[firefox-esr-l10n-az]Not affected
Source package: [firefox-esr]
Details (4)
- 140.12.0esr-1~deb12u1 · all · bookworm
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.12.0esr-1~deb12u1 · all · bookworm
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.14.0esr-1~deb12u1 · all · bookworm-security
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.14.0esr-1~deb12u1 · all · bookworm-security
  Not affected
  nvd · firefox-esr · debian · bookworm
[firefox-esr-l10n-be]Not affected
Source package: [firefox-esr]
Details (4)
- 140.12.0esr-1~deb12u1 · all · bookworm
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.12.0esr-1~deb12u1 · all · bookworm
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.14.0esr-1~deb12u1 · all · bookworm-security
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.14.0esr-1~deb12u1 · all · bookworm-security
  Not affected
  nvd · firefox-esr · debian · bookworm
[firefox-esr-l10n-bg]Not affected
Source package: [firefox-esr]
Details (4)
- 140.12.0esr-1~deb12u1 · all · bookworm
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.12.0esr-1~deb12u1 · all · bookworm
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.14.0esr-1~deb12u1 · all · bookworm-security
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.14.0esr-1~deb12u1 · all · bookworm-security
  Not affected
  nvd · firefox-esr · debian · bookworm
[firefox-esr-l10n-bn]Not affected
Source package: [firefox-esr]
Details (4)
- 140.12.0esr-1~deb12u1 · all · bookworm
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.12.0esr-1~deb12u1 · all · bookworm
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.14.0esr-1~deb12u1 · all · bookworm-security
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.14.0esr-1~deb12u1 · all · bookworm-security
  Not affected
  nvd · firefox-esr · debian · bookworm
[firefox-esr-l10n-br]Not affected
Source package: [firefox-esr]
Details (4)
- 140.12.0esr-1~deb12u1 · all · bookworm
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.12.0esr-1~deb12u1 · all · bookworm
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.14.0esr-1~deb12u1 · all · bookworm-security
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.14.0esr-1~deb12u1 · all · bookworm-security
  Not affected
  nvd · firefox-esr · debian · bookworm
[firefox-esr-l10n-bs]Not affected
Source package: [firefox-esr]
Details (4)
- 140.12.0esr-1~deb12u1 · all · bookworm
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.12.0esr-1~deb12u1 · all · bookworm
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.14.0esr-1~deb12u1 · all · bookworm-security
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.14.0esr-1~deb12u1 · all · bookworm-security
  Not affected
  nvd · firefox-esr · debian · bookworm
[firefox-esr-l10n-ca]Not affected
Source package: [firefox-esr]
Details (4)
- 140.12.0esr-1~deb12u1 · all · bookworm
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.12.0esr-1~deb12u1 · all · bookworm
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.14.0esr-1~deb12u1 · all · bookworm-security
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.14.0esr-1~deb12u1 · all · bookworm-security
  Not affected
  nvd · firefox-esr · debian · bookworm
[firefox-esr-l10n-cak]Not affected
Source package: [firefox-esr]
Details (4)
- 140.12.0esr-1~deb12u1 · all · bookworm
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.12.0esr-1~deb12u1 · all · bookworm
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.14.0esr-1~deb12u1 · all · bookworm-security
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.14.0esr-1~deb12u1 · all · bookworm-security
  Not affected
  nvd · firefox-esr · debian · bookworm
[firefox-esr-l10n-ca-valencia]Not affected
Source package: [firefox-esr]
Details (4)
- 140.12.0esr-1~deb12u1 · all · bookworm
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.12.0esr-1~deb12u1 · all · bookworm
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.14.0esr-1~deb12u1 · all · bookworm-security
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.14.0esr-1~deb12u1 · all · bookworm-security
  Not affected
  nvd · firefox-esr · debian · bookworm
[firefox-esr-l10n-cs]Not affected
Source package: [firefox-esr]
Details (4)
- 140.12.0esr-1~deb12u1 · all · bookworm
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.12.0esr-1~deb12u1 · all · bookworm
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.14.0esr-1~deb12u1 · all · bookworm-security
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.14.0esr-1~deb12u1 · all · bookworm-security
  Not affected
  nvd · firefox-esr · debian · bookworm
[firefox-esr-l10n-cy]Not affected
Source package: [firefox-esr]
Details (4)
- 140.12.0esr-1~deb12u1 · all · bookworm
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.12.0esr-1~deb12u1 · all · bookworm
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.14.0esr-1~deb12u1 · all · bookworm-security
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.14.0esr-1~deb12u1 · all · bookworm-security
  Not affected
  nvd · firefox-esr · debian · bookworm
[firefox-esr-l10n-da]Not affected
Source package: [firefox-esr]
Details (4)
- 140.12.0esr-1~deb12u1 · all · bookworm
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.12.0esr-1~deb12u1 · all · bookworm
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.14.0esr-1~deb12u1 · all · bookworm-security
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.14.0esr-1~deb12u1 · all · bookworm-security
  Not affected
  nvd · firefox-esr · debian · bookworm
[firefox-esr-l10n-de]Not affected
Source package: [firefox-esr]
Details (4)
- 140.12.0esr-1~deb12u1 · all · bookworm
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.12.0esr-1~deb12u1 · all · bookworm
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.14.0esr-1~deb12u1 · all · bookworm-security
  Not affected
  nvd · firefox-esr · debian · bookworm
- 140.14.0esr-1~deb12u1 · all · bookworm-security
  Not affected
  nvd · firefox-esr · debian · bookworm

Next results

Observed: Oct 27, 2026, 7:31:02 PM UTC

References

[CERT-Bund public advisories] · [Debian Security Tracker] · [FIRST EPSS] · [National Vulnerability Database (NVD)] · [OSV Package Vulnerability Database] · [Red Hat security advisories and VEX] · [SUSE security advisories and VEX]