6.5

CVE-2026-8971: mozilla firefox Origin Validation Error

CVSS: 6.5v3.1MediumAnalyzed
AliasesUBUNTU-CVE-2026-8971CGA-8wv3-x3x3-443cCGA-r6w8-x3c9-2wgw
Published 19-05-2026Last modified 19-05-2026
Open JSON

Vulnerability summary

CVE-2026-8971 is a medium (CVSS 6.5) Origin Validation Error vulnerability in mozilla firefox. EPSS estimates a 0.17% chance of exploitation in the next 30 days, higher than 6.5% of scored vulnerabilities.

Overall risk
26/100
0100
Medium · default modelHow is this calculated?
CVSS score
6.5/10
010
Medium · v3.1 (CVE.org)
EPSS score
0.17%
0%100%
Low · -0.03 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 2 · Related 3
OPENSUSE-SU-2026:10863-1OPENSUSE-SU-2026:11373-1CGA-JX7V-8W67-HCJQ

Timeline

  1. 19-05-2026
    PublishedVulnerability first disclosed.
  2. 19-05-2026
    Last modifiedVulnerability information updated.

Description

Same-origin policy bypass in the Networking: JAR component. This vulnerability was fixed in Firefox 151 and Thunderbird 151.

CVSS metrics

3 scores · 3 sources · 1 version

EPSS trend

Probability

0.17%

Chance of exploitation in the next 30 days

Percentile

7%

Versus all other CVEs

30-day change

-0.03 pp

From 0.21% on 21-09-2026

21-09-202621-10-2026
EPSS score
0.17%

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
Chainguard1 product
  • firefox< 151-r0
Wolfi1 product
  • firefox< 151-r0

4 vendors · 12 products

References

6 links