5.4

CVE-2026-12321: JIT miscompilation in the JavaScript: WebAssembly component

Analyzed
AliasesUBUNTU-CVE-2026-12321CGA-5cm7-c85r-pvh8CGA-f6jf-v38g-259p
Published 16-06-2026Last modified 16-06-2026

Vulnerability summary

CVE-2026-12321 is a medium (CVSS 5.4) vulnerability in mozilla firefox. EPSS estimates a 0.16% chance of exploitation in the next 30 days, higher than 4.6% of scored vulnerabilities.

Overall risk
22/100
0100
Low · default modelHow is this calculated?
CVSS score
5.4/10
010
Medium · v3.1 (CVE.org)
EPSS score
0.16%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 2 · Related 3
OPENSUSE-SU-2026:11052-1OPENSUSE-SU-2026:11373-1CGA-GG5C-Q35P-45J3

Timeline

  1. 16-06-2026
    PublishedVulnerability first disclosed.
  2. 16-06-2026
    Last modifiedVulnerability information updated.

Description

JIT miscompilation in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox 152 and Thunderbird 152.

CVSS metrics

3 scores · 3 sources · 1 version

EPSS trend

Probability

0.16%

Chance of exploitation in the next 30 days

Percentile

5%

Versus all other CVEs

30-day change

No change 0.00 pp

From 0.16% on 22-09-2026

22-09-202622-10-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Ubuntu8 products
  • mozjs102All versions (No fix recorded)
  • mozjs115All versions (No fix recorded)
  • mozjs38All versions (No fix recorded)
  • mozjs52All versions (No fix recorded)
  • mozjs68All versions (No fix recorded)
Mozilla2 products
Chainguard1 product
  • firefox< 152.0.1-r0
Wolfi1 product
  • firefox< 152.0.1-r0

4 vendors · 12 products

References

6 links