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CVE-2026-75874: mozilla firefox Protection Mechanism Failure

CVSS: 10.0v3.1CriticalModified
AliasesUBUNTU-CVE-2026-75874DEBIAN-CVE-2026-75874CGA-598j-75xv-jjv8
Published 18-08-2026Last modified 01-09-2026
Open JSON

Vulnerability summary

CVE-2026-75874 is a critical (CVSS 10.0) Protection Mechanism Failure vulnerability in mozilla firefox. EPSS estimates a 0.46% chance of exploitation in the next 30 days, higher than 38.1% of scored vulnerabilities.

Overall risk
70/100
0100
High · default modelHow is this calculated?
CVSS score
10.0/10
010
Critical · v3.1 (CVE.org)
EPSS score
0.46%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 33 · Related 11
MGASA-2026-0387MGASA-2026-0388OPENSUSE-SU-2026:11580-1OPENSUSE-SU-2026:11666-1OPENSUSE-SU-2026:11678-1OPENSUSE-SU-2026:21853-1

Timeline

  1. 18-08-2026
    PublishedVulnerability first disclosed.
  2. 01-09-2026
    Last modifiedVulnerability information updated.

Description

Sandbox escape in the Remote Settings Client component. This vulnerability was fixed in Firefox 154, Thunderbird 154, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 140.15, and Thunderbird 153.2.

CVSS metrics

4 scores · 4 sources · 1 version

EPSS trend

Probability

0.46%

Chance of exploitation in the next 30 days

Percentile

38%

Versus all other CVEs

30-day change

0.00 pp

From 0.46% on 19-09-2026

19-09-202619-10-2026
EPSS score
0.46%

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)
Chainguard2 products
  • firefox< 154.0-r0
  • firefox-docker-selenium-compat< 154.0-r0
Debian2 products
  • firefox-esr< 140.15.0esr-1~deb12u1 | < 140.15.0esr-1~deb13u1 | < 140.15.0esr-1
  • thunderbird< 1:140.15.0esr-1~deb12u1 | < 1:140.15.0esr-1~deb13u1 | < 1:153.2.0esr-1
Mozilla2 products
Wolfi2 products
  • firefox< 154.0-r0
  • firefox-docker-selenium-compat< 154.0-r0

5 vendors · 16 products

References

12 links
Show all 12 references