Vulnerability · Published May 12, 2026 · Assigned by mozilla
CVE-2026-8389JIT miscompilation in the JavaScript Engine: JIT component
High 8.8
In plain English
A high-severity type confusion in Firefox from Mozilla. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 37% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code.
Severity (CVSS 3.1)8.8High
Exploit odds (30 days)0.4%top 63.3% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack tooling1Public PoC
Official description
JIT miscompilation in the JavaScript Engine: JIT component. This vulnerability was fixed in Firefox 150.0.3.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu:22.04:LTS | mozjs102 | no fix listed | UBUNTU-CVE-2026-8389 |
| Ubuntu:24.04:LTS | mozjs102 | no fix listed | UBUNTU-CVE-2026-8389 |
| Ubuntu:24.04:LTS | mozjs115 | no fix listed | UBUNTU-CVE-2026-8389 |
| Ubuntu:22.04:LTS | mozjs78 | no fix listed | UBUNTU-CVE-2026-8389 |
| Ubuntu:22.04:LTS | mozjs91 | no fix listed | UBUNTU-CVE-2026-8389 |
| Ubuntu:22.04:LTS | thunderbird | no fix listed | UBUNTU-CVE-2026-8389 |
Affected products (as reported)
Weakness: CWE-686, CWE-843, CWE-119, CWE-733 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=2036983
- https://www.mozilla.org/security/advisories/mfsa2026-45/
- https://github.com/crixpwn/CVE-2026-8389 exploit
- https://access.redhat.com/security/cve/CVE-2026-8389 vdb-entry, x_refsource_REDHAT
- RHBZ#2476466 issue-tracking, x_refsource_REDHAT
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-8389.json x_sadp-csaf-vex