9.8

CVE-2026-84135: mozilla firefox_mobile Improper Input Validation

CVSS: 9.8v3.1CriticalModified
AliasesUBUNTU-CVE-2026-84135
Published 01-09-2026Last modified 03-09-2026
Open JSON

Vulnerability summary

CVE-2026-84135 is a critical (CVSS 9.8) Improper Input Validation vulnerability in mozilla firefox_mobile. EPSS estimates a 0.45% chance of exploitation in the next 30 days, higher than 37.9% of scored vulnerabilities.

Overall risk
70/100
0100
High · default modelHow is this calculated?
CVSS score
9.8/10
010
Critical · v3.1 (CVE.org)
EPSS score
0.45%
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 1
OPENSUSE-SU-2026:11677-1

Timeline

  1. 01-09-2026
    PublishedVulnerability first disclosed.
  2. 03-09-2026
    Last modifiedVulnerability information updated.

Description

Other issue in Firefox Focus for Android. This vulnerability was fixed in Firefox 155.

CVSS metrics

3 scores · 3 sources · 1 version

EPSS trend

Probability

0.45%

Chance of exploitation in the next 30 days

Percentile

38%

Versus all other CVEs

30-day change

+0.20 pp

From 0.25% on 21-09-2026

21-09-202621-10-2026
EPSS score
0.45%

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)
Mozilla1 product

2 vendors · 9 products

References

5 links