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Vulnerability · Published Oct 27, 2026 · Assigned by mozilla

CVE-2026-117934Use-after-free in the Layout component

Medium 6.3

In plain English

A medium-severity use-after-free in Firefox from Mozilla. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 20% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)6.3Medium
Exploit odds (30 days)0.3%top 80.2% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

Use-after-free in the Layout component. This vulnerability was fixed in Firefox 159, Firefox ESR 115.44, Firefox ESR 153.6, Thunderbird 159, and Thunderbird 153.6.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12firefox-esr153.6.0esr-1~deb12u2DEBIAN-CVE-2026-117934
Debian:13firefox-esr153.6.0esr-1~deb13u1DEBIAN-CVE-2026-117934
Debian:14firefox-esrno fix listedDEBIAN-CVE-2026-117934
Debian:12thunderbird1:153.6.0esr-1~deb12u2DEBIAN-CVE-2026-117934
Debian:13thunderbird1:153.6.0esr-1~deb13u1DEBIAN-CVE-2026-117934
Debian:14thunderbirdno fix listedDEBIAN-CVE-2026-117934
Ubuntu:22.04:LTSmozjs102no fix listedUBUNTU-CVE-2026-117934
Ubuntu:24.04:LTSmozjs102no fix listedUBUNTU-CVE-2026-117934
Ubuntu:24.04:LTSmozjs115no fix listedUBUNTU-CVE-2026-117934
Ubuntu:22.04:LTSmozjs78no fix listedUBUNTU-CVE-2026-117934
Ubuntu:22.04:LTSmozjs91no fix listedUBUNTU-CVE-2026-117934
Ubuntu:22.04:LTSthunderbirdno fix listedUBUNTU-CVE-2026-117934

Affected products (as reported)

VendorProductVersions
Mozilla Firefox see references
Mozilla Thunderbird see references

Weakness: CWE-416 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L

References