8.1

CVE-2026-74983: mozilla firefox Protection Mechanism Failure

CVSS: 8.1v3.1HighAnalyzed
AliasesUBUNTU-CVE-2026-74983DEBIAN-CVE-2026-74983
Published 18-08-2026Last modified 17-09-2026
Open JSON

Vulnerability summary

CVE-2026-74983 is a high (CVSS 8.1) Protection Mechanism Failure vulnerability in mozilla firefox. EPSS estimates a 0.43% chance of exploitation in the next 30 days, higher than 36.3% of scored vulnerabilities.

Overall risk
32/100
0100
Medium · default modelHow is this calculated?
CVSS score
8.1/10
010
High · v3.1 (CVE.org)
EPSS score
0.43%
0%100%
Low · +0.11 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 27 · Related 14
MGASA-2026-0345MGASA-2026-0346OPENSUSE-SU-2026:11546-1OPENSUSE-SU-2026:11558-1OPENSUSE-SU-2026:11580-1OPENSUSE-SU-2026:21594-1

Timeline

  1. 18-08-2026
    PublishedVulnerability first disclosed.
  2. 17-09-2026
    Last modifiedVulnerability information updated.

Description

Mitigation bypass in the Data Loss Prevention component. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

CVSS metrics

4 scores · 4 sources · 1 version

EPSS trend

Probability

0.43%

Chance of exploitation in the next 30 days

Percentile

36%

Versus all other CVEs

30-day change

+0.11 pp

From 0.33% on 19-09-2026

19-09-202619-10-2026
EPSS score
0.43%

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)
Debian2 products
  • firefox-esr< 140.14.0esr-1~deb12u1 | < 140.14.0esr-1~deb13u1 | < 140.14.0esr-2
  • thunderbird< 1:140.14.0esr-1~deb12u1 | < 1:140.14.0esr-1~deb13u1 | < 1:140.14.0esr-1
Mozilla2 products

3 vendors · 12 products

References

13 links
Show all 13 references