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CVE-2026-2761: mozilla firefox Protection Mechanism Failure

CVSS: 10.0v3.1CriticalModified
AliasesUBUNTU-CVE-2026-2761DEBIAN-CVE-2026-2761CGA-gxcq-5229-r8w4
Published 24-02-2026Last modified 15-07-2026
Open JSON

Vulnerability summary

CVE-2026-2761 is a critical (CVSS 10.0) Protection Mechanism Failure vulnerability in mozilla firefox. EPSS estimates a 0.63% chance of exploitation in the next 30 days, higher than 49.1% 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
0.63%
0%100%
Low · +0.23 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 39 · Related 9
DLA-4495-1DLA-4496-1DSA-6148-1DSA-6152-1MGASA-2026-0052MGASA-2026-0053

Timeline

  1. 24-02-2026
    PublishedVulnerability first disclosed.
  2. 15-07-2026
    Last modifiedVulnerability information updated.

Description

Sandbox escape in the Graphics: WebRender component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

CVSS metrics

6 scores · 6 sources · 1 version

EPSS trend

Probability

0.63%

Chance of exploitation in the next 30 days

Percentile

49%

Versus all other CVEs

30-day change

+0.23 pp

From 0.40% on 20-09-2026

20-09-202620-10-2026
EPSS score
0.63%

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< 148.0-r0
  • firefox-esr< 140.8.0-r0
Debian2 products
  • firefox-esr< 140.8.0esr-1~deb12u1 | < 140.8.0esr-1~deb13u1 | < 140.8.0esr-1
  • thunderbird< 1:140.8.0esr-1~deb12u1 | < 1:140.8.0esr-1~deb13u1 | < 1:140.8.0esr-1
Mozilla2 products
Wolfi1 product
  • firefox< 148.0-r0

5 vendors · 15 products

References

39 links
Show all 39 references