9.6

CVE-2026-100804: mozilla firefox Use After Free

CVSS: 9.6v3.1CriticalAnalyzed
AliasesUBUNTU-CVE-2026-100804
Published 29-09-2026Last modified 30-09-2026
Open JSON

Vulnerability summary

CVE-2026-100804 is a critical (CVSS 9.6) Use After Free vulnerability in mozilla firefox. EPSS estimates a 0.28% chance of exploitation in the next 30 days, higher than 19.6% of scored vulnerabilities.

Overall risk
70/100
0100
High · default modelHow is this calculated?
CVSS score
9.6/10
010
Critical · v3.1 (CVE.org)
EPSS score
0.28%
0%100%
Low · Change unavailable
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 1 · Related 1
OPENSUSE-SU-2026:12097-1

Timeline

  1. 29-09-2026
    PublishedVulnerability first disclosed.
  2. 30-09-2026
    Last modifiedVulnerability information updated.

Description

Sandbox escape due to use-after-free in the Preferences: Backend component. This vulnerability was fixed in Thunderbird 157 and Firefox 157.

CVSS metrics

3 scores · 3 sources · 1 version

EPSS trend

Probability

0.28%

Chance of exploitation in the next 30 days

Percentile

20%

Versus all other CVEs

30-day change

Change unavailable

Change unavailable

30-09-202621-10-2026
EPSS score
0.28%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

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

2 vendors · 10 products

References

6 links