CVE-2026-7321

Name: CVE-2026-7321
Creator: NVD / NIST
Published: 2026-04-28T15:16:37.55+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.6/10EPSS 0.26%

Last modified Jun 17, 2026

CVE-2026-7321 is a critical-severity vulnerability rated 9.6/10 on the CVSS scale. Sandbox escape due to incorrect boundary conditions in the WebRTC: Networking component. This vulnerability was fixed in Firefox 150, Thunderbird 150, Firefox ESR 140.10.1, and Thunderbird 140.10.1.. EPSS estimates a 0.26% chance of exploitation in the next 30 days.

Description

Sandbox escape due to incorrect boundary conditions in the WebRTC: Networking component. This vulnerability was fixed in Firefox 150, Thunderbird 150, Firefox ESR 140.10.1, and Thunderbird 140.10.1.

Metrics

CVSS 3.1

9.6/10

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

EPSS Probability

0.26%

17.1th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-120

Affected Software

Vendor	Product	Versions
Mozilla	Firefox	< 140.10.1
Mozilla	Firefox	< 150.0
Mozilla	Thunderbird	< 140.10.1
Mozilla	Thunderbird	< 150.0

References

https://bugzilla.mozilla.org/show_bug.cgi?id=2029461Permissions Required
https://www.mozilla.org/security/advisories/mfsa2026-30/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-33/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-36/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-39/Vendor Advisory

Timeline

Published: Apr 28, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-7321?

Sandbox escape due to incorrect boundary conditions in the WebRTC: Networking component. This vulnerability was fixed in Firefox 150, Thunderbird 150, Firefox ESR 140.10.1, and Thunderbird 140.10.1.

How severe is CVE-2026-7321?

CVE-2026-7321 has a CVSS score of 9.6/10 (CRITICAL severity). The EPSS model estimates a 0.26% probability of exploitation in the next 30 days.

How do I fix CVE-2026-7321?

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-2026-7321?

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

Scan your code now

Source: NVD / NIST