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Vulnerability · Published Oct 27, 2026 · Assigned by mozilla

CVE-2026-117889Incorrect boundary conditions in the JavaScript Engine component

High 7.3

In plain English

A high-severity memory corruption 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 0.4% (higher than 30% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.3High
Exploit odds (30 days)0.4%top 70.3% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

Incorrect boundary conditions in the JavaScript Engine 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-2026-117889
Debian:13firefox-esr153.6.0esr-1~deb13u1DEBIAN-CVE-2026-117889
Debian:14firefox-esrno fix listedDEBIAN-CVE-2026-117889
Debian:12thunderbird1:153.6.0esr-1~deb12u2DEBIAN-CVE-2026-117889
Debian:13thunderbird1:153.6.0esr-1~deb13u1DEBIAN-CVE-2026-117889
Debian:14thunderbirdno fix listedDEBIAN-CVE-2026-117889
Ubuntu:22.04:LTSmozjs102no fix listedUBUNTU-CVE-2026-117889
Ubuntu:24.04:LTSmozjs102no fix listedUBUNTU-CVE-2026-117889
Ubuntu:24.04:LTSmozjs115no fix listedUBUNTU-CVE-2026-117889
Ubuntu:22.04:LTSmozjs78no fix listedUBUNTU-CVE-2026-117889
Ubuntu:22.04:LTSmozjs91no fix listedUBUNTU-CVE-2026-117889
Ubuntu:22.04:LTSthunderbirdno fix listedUBUNTU-CVE-2026-117889

Affected products (as reported)

VendorProductVersions
Mozilla Firefox see references
Mozilla Thunderbird see references

Weakness: CWE-119 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

References