6.3

CVE-2026-92039: mozilla firefox Protection Mechanism Failure

CVSS: 6.3v3.1MediumAnalyzed
AliasesUBUNTU-CVE-2026-92039DEBIAN-CVE-2026-92039
Published 15-09-2026Last modified 21-09-2026
Open JSON

Vulnerability summary

CVE-2026-92039 is a medium (CVSS 6.3) Protection Mechanism Failure vulnerability in mozilla firefox. EPSS estimates a 0.20% chance of exploitation in the next 30 days, higher than 9.2% of scored vulnerabilities.

Overall risk
25/100
0100
Medium · default modelHow is this calculated?
CVSS score
6.3/10
010
Medium · v3.1 (CVE.org)
EPSS score
0.20%
0%100%
Low · +0.04 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 10 · Related 8
MGASA-2026-0441MGASA-2026-0449OPENSUSE-SU-2026:11796-1OPENSUSE-SU-2026:11826-1OPENSUSE-SU-2026:12098-1OPENSUSE-SU-2026:21951-1

Timeline

  1. 15-09-2026
    PublishedVulnerability first disclosed.
  2. 21-09-2026
    Last modifiedVulnerability information updated.

Description

Mitigation bypass in the DOM: Notifications component. This vulnerability was fixed in Firefox 156, Firefox ESR 153.3, Thunderbird 156, and Thunderbird 153.3.

CVSS metrics

4 scores · 4 sources · 1 version

EPSS trend

Probability

0.20%

Chance of exploitation in the next 30 days

Percentile

9%

Versus all other CVEs

30-day change

+0.04 pp

From 0.16% on 20-09-2026

20-09-202620-10-2026
EPSS score
0.20%

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
Debian1 product
  • thunderbird< 1:153.3.0esr-1

3 vendors · 11 products

References

9 links