9.1

CVE-2026-16406: mozilla firefox Protection Mechanism Failure

CVSS: 9.1v3.1CriticalModified
AliasesUBUNTU-CVE-2026-16406CGA-2jgw-vq6r-2jgvCGA-r7rq-xm7f-p7v8
Published 21-07-2026Last modified 22-07-2026
Open JSON

Vulnerability summary

CVE-2026-16406 is a critical (CVSS 9.1) Protection Mechanism Failure vulnerability in mozilla firefox. EPSS estimates a 0.25% chance of exploitation in the next 30 days, higher than 15.4% of scored vulnerabilities.

Overall risk
70/100
0100
High · default modelHow is this calculated?
CVSS score
9.1/10
010
Critical · v3.1 (CVE.org)
EPSS score
0.25%
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 8 · Related 9
OPENSUSE-SU-2026:11358-1OPENSUSE-SU-2026:11373-1OPENSUSE-SU-2026:21713-1SUSE-SU-2026:23411-1SUSE-SU-2026:23590-1SUSE-SU-2026:4140-1

Timeline

  1. 21-07-2026
    PublishedVulnerability first disclosed.
  2. 22-07-2026
    Last modifiedVulnerability information updated.

Description

Mitigation bypass in the Networking component. This vulnerability was fixed in Firefox 153 and Thunderbird 153.

CVSS metrics

3 scores · 3 sources · 1 version

EPSS trend

Probability

0.25%

Chance of exploitation in the next 30 days

Percentile

15%

Versus all other CVEs

30-day change

0.00 pp

From 0.25% on 21-09-2026

21-09-202621-10-2026
EPSS score
0.25%

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< 153.0-r0
  • firefox-docker-selenium-compat< 153.0-r0
Wolfi2 products
  • firefox< 153.0-r0
  • firefox-docker-selenium-compat< 153.0-r0
Mozilla1 product

4 vendors · 13 products

References

6 links