CVE-2026-8971

Name: CVE-2026-8971
Creator: NVD / NIST
Published: 2026-05-19T14:16:53.633+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.5/10EPSS 0.21%

Last modified Jun 17, 2026

CVE-2026-8971 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. Same-origin policy bypass in the Networking: JAR component. This vulnerability was fixed in Firefox 151 and Thunderbird 151.. EPSS estimates a 0.21% chance of exploitation in the next 30 days.

Description

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

Metrics

CVSS 3.1

6.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

EPSS Probability

0.21%

10.7th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-346

Affected Software

Vendor	Product	Versions
Mozilla	Firefox	< 151.0.0
Mozilla	Thunderbird	< 151.0.0

References

https://bugzilla.mozilla.org/show_bug.cgi?id=2032604Permissions Required
https://www.mozilla.org/security/advisories/mfsa2026-46/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-50/Vendor Advisory

Timeline

Published: May 19, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-8971?

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

How severe is CVE-2026-8971?

CVE-2026-8971 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 0.21% probability of exploitation in the next 30 days.

How do I fix CVE-2026-8971?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-8971?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST