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Vulnerability · Published May 12, 2026 · Assigned by mozilla

CVE-2026-8388Incorrect boundary conditions in the JavaScript Engine: JIT component

Medium 6.5

In plain English

A medium-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 0.2% (higher than 16% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code. Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)6.5Medium
Exploit odds (30 days)0.2%top 84.4% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack tooling1Public PoC

Official description

Incorrect boundary conditions in the JavaScript Engine: JIT component. This vulnerability was fixed in Firefox 150.0.3, Firefox ESR 115.36, Firefox ESR 140.11, and Thunderbird 140.11.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
AlmaLinux:10firefox140.11.0-1.el10_2ALSA-2026:21380
AlmaLinux:8firefox140.11.0-1.el8_10.alma.1ALSA-2026:21382
AlmaLinux:9firefox140.11.0-1.el9_8.alma.1ALSA-2026:21378
AlmaLinux:9firefox-x11140.11.0-1.el9_8.alma.1ALSA-2026:21378
AlmaLinux:10thunderbird140.11.0-1.el10_2.alma.1ALSA-2026:22325
AlmaLinux:8thunderbird140.11.0-1.el8_10.alma.1ALSA-2026:22643
AlmaLinux:9thunderbird140.11.0-1.el9_8.alma.1ALSA-2026:21381
Debian:12firefox-esr140.11.0esr-1~deb12u1DEBIAN-CVE-2026-8388
Debian:13firefox-esr140.11.0esr-1~deb13u1DEBIAN-CVE-2026-8388
Debian:14firefox-esr140.11.0esr-1DEBIAN-CVE-2026-8388
Debian:12thunderbird1:140.11.0esr-1~deb12u1DEBIAN-CVE-2026-8388
Debian:13thunderbird1:140.11.0esr-1~deb13u1DEBIAN-CVE-2026-8388
Debian:14thunderbird1:140.11.0esr-1DEBIAN-CVE-2026-8388
Rocky Linux:10firefox0:140.11.0-1.el10_2RLSA-2026:21380
Rocky Linux:8firefox0:140.11.0-1.el8_10RLSA-2026:21382
Rocky Linux:9firefox0:140.11.0-1.el9_8RLSA-2026:21378
Rocky Linux:10thunderbird0:140.11.0-1.el10_2RLSA-2026:22325
Rocky Linux:8thunderbird0:140.11.0-1.el8_10RLSA-2026:22643
Rocky Linux:9thunderbird0:140.11.0-1.el9_8RLSA-2026:21381
Ubuntu:22.04:LTSmozjs102no fix listedUBUNTU-CVE-2026-8388
Ubuntu:24.04:LTSmozjs102no fix listedUBUNTU-CVE-2026-8388
Ubuntu:24.04:LTSmozjs115no fix listedUBUNTU-CVE-2026-8388
Ubuntu:22.04:LTSmozjs78no fix listedUBUNTU-CVE-2026-8388
Ubuntu:22.04:LTSmozjs91no fix listedUBUNTU-CVE-2026-8388
Ubuntu:22.04:LTSthunderbirdno fix listedUBUNTU-CVE-2026-8388

Affected products (as reported)

VendorProductVersions
Mozilla Firefox see references
Mozilla Thunderbird see references

Weakness: CWE-119, CWE-787 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

References