CVE-2026-12300

Name: CVE-2026-12300
Creator: NVD / NIST
Published: 2026-06-16T13:16:30.267+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.3/10EPSS 0.25%

Last modified Jun 18, 2026

CVE-2026-12300 is a medium-severity vulnerability rated 5.3/10 on the CVSS scale. Memory safety bug fixed in Firefox 152. This vulnerability was fixed in Firefox 152 and Thunderbird 152.. EPSS estimates a 0.25% chance of exploitation in the next 30 days.

Description

Memory safety bug fixed in Firefox 152. This vulnerability was fixed in Firefox 152 and Thunderbird 152.

Metrics

CVSS 3.1

5.3/10

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

EPSS Probability

0.25%

16.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-119

Affected Software

Vendor	Product	Versions
Mozilla	Firefox	< 152.0.0
Mozilla	Thunderbird	< 152.0.0

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1704114Permissions Required
https://www.mozilla.org/security/advisories/mfsa2026-57/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-60/Vendor Advisory

Timeline

Published: Jun 16, 2026
Last Modified: Jun 18, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2026-12300?

Memory safety bug fixed in Firefox 152. This vulnerability was fixed in Firefox 152 and Thunderbird 152.

How severe is CVE-2026-12300?

CVE-2026-12300 has a CVSS score of 5.3/10 (MEDIUM severity). The EPSS model estimates a 0.25% probability of exploitation in the next 30 days.

How do I fix CVE-2026-12300?

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-2026-12300?

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

Scan your code now

Source: NVD / NIST