8.8

CVE-2026-84128: mozilla firefox Improper Access Control

CVSS: 8.8v3.1HighAnalyzed
AliasesUBUNTU-CVE-2026-84128CGA-3pp9-53xm-7254CGA-74mj-44w8-ghjm
Published 01-09-2026Last modified 02-09-2026
Open JSON

Vulnerability summary

CVE-2026-84128 is a high (CVSS 8.8) Improper Access Control vulnerability in mozilla firefox. EPSS estimates a 0.44% chance of exploitation in the next 30 days, higher than 36.8% of scored vulnerabilities.

Overall risk
35/100
0100
Medium · default modelHow is this calculated?
CVSS score
8.8/10
010
High · v3.1 (CVE.org)
EPSS score
0.44%
0%100%
Low · +0.20 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 1 · Related 2
OPENSUSE-SU-2026:11677-1CGA-VP64-Q5J7-FRJR

Timeline

  1. 01-09-2026
    PublishedVulnerability first disclosed.
  2. 02-09-2026
    Last modifiedVulnerability information updated.

Description

Privilege escalation in the WebDriver BiDi component. This vulnerability was fixed in Firefox 155 and Thunderbird 155.

CVSS metrics

3 scores · 3 sources · 1 version

EPSS trend

Probability

0.44%

Chance of exploitation in the next 30 days

Percentile

37%

Versus all other CVEs

30-day change

+0.20 pp

From 0.23% on 21-09-2026

21-09-202621-10-2026
EPSS score
0.44%

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< 155.0.1-r0
  • firefox-docker-selenium-compat< 155.0.1-r0
Mozilla2 products
Wolfi2 products
  • firefox< 155.0.1-r0
  • firefox-docker-selenium-compat< 155.0.1-r0

4 vendors · 14 products

References

6 links