CVE-2026-8391

NameCVE-2026-8391
DescriptionOther issue in the JavaScript Engine component. This vulnerability was fixed in Firefox 150.0.3, Firefox ESR 115.36, Firefox ESR 140.11, and Thunderbird 140.11.
SourceCVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
ReferencesDLA-4592-1, DLA-4594-1, DSA-6283-1, DSA-6288-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
firefox (PTS)sid151.0.1-1fixed
firefox-esr (PTS)bullseye115.14.0esr-1~deb11u1vulnerable
bullseye (security)140.11.0esr-1~deb11u1fixed
bookworm140.10.2esr-1~deb12u1vulnerable
bookworm (security)140.11.0esr-1~deb12u1fixed
trixie140.10.2esr-1~deb13u1vulnerable
trixie (security)140.11.0esr-1~deb13u1fixed
forky140.10.2esr-1vulnerable
sid140.11.0esr-1fixed
thunderbird (PTS)bullseye1:115.12.0-1~deb11u1vulnerable
bullseye (security)1:140.11.0esr-1~deb11u1fixed
bookworm1:140.10.1esr-1~deb12u1vulnerable
bookworm (security)1:140.11.0esr-1~deb12u1fixed
trixie1:140.10.1esr-1~deb13u1vulnerable
trixie (security)1:140.11.0esr-1~deb13u1fixed
forky1:140.10.2esr-1vulnerable
sid1:140.11.0esr-1fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
firefoxsource(unstable)150.0.3-1
firefox-esrsourcebullseye140.11.0esr-1~deb11u1DLA-4592-1
firefox-esrsourcebookworm140.11.0esr-1~deb12u1DSA-6283-1
firefox-esrsourcetrixie140.11.0esr-1~deb13u1DSA-6283-1
firefox-esrsource(unstable)140.11.0esr-1
thunderbirdsourcebullseye1:140.11.0esr-1~deb11u1DLA-4594-1
thunderbirdsourcebookworm1:140.11.0esr-1~deb12u1DSA-6288-1
thunderbirdsourcetrixie1:140.11.0esr-1~deb13u1DSA-6288-1
thunderbirdsource(unstable)1:140.11.0esr-1

Notes

https://www.mozilla.org/en-US/security/advisories/mfsa2026-45/#CVE-2026-8391
https://www.mozilla.org/en-US/security/advisories/mfsa2026-48/#CVE-2026-8391
https://www.mozilla.org/en-US/security/advisories/mfsa2026-51/#CVE-2026-8391

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