CVE-2025-0240

Name: CVE-2025-0240
Creator: NVD / NIST
Published: 2025-01-07T16:15:38.663+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 4/10EPSS 0.66%

Last modified Jun 17, 2026

CVE-2025-0240 is a medium-severity vulnerability rated 4/10 on the CVSS scale. Parsing a JavaScript module as JSON could, under some circumstances, cause cross-compartment access, which may result in a use-after-free. This vulnerability was fixed in Firefox 134, Firefox ESR 128.6, Thunderbird 134, and Thunderbird 128.6.. EPSS estimates a 0.66% chance of exploitation in the next 30 days.

Description

Parsing a JavaScript module as JSON could, under some circumstances, cause cross-compartment access, which may result in a use-after-free. This vulnerability was fixed in Firefox 134, Firefox ESR 128.6, Thunderbird 134, and Thunderbird 128.6.

Metrics

CVSS 3.1

4/10

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

EPSS Probability

0.66%

47.1th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-416

Affected Software

Vendor	Product	Versions
Mozilla	Firefox	< 128.6.0
Mozilla	Firefox	< 134.0
Mozilla	Thunderbird	< 128.6.0
Mozilla	Thunderbird	>= 129.0, < 134.0

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1929623Issue Tracking, Permissions Required
https://www.mozilla.org/security/advisories/mfsa2025-01/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2025-02/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2025-04/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2025-05/Vendor Advisory
https://lists.debian.org/debian-lts-announce/2025/01/msg00004.html

Timeline

Published: Jan 7, 2025
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2025-0240?

How severe is CVE-2025-0240?

CVE-2025-0240 has a CVSS score of 4/10 (MEDIUM severity). The EPSS model estimates a 0.66% probability of exploitation in the next 30 days.

How do I fix CVE-2025-0240?

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-2025-0240?

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

Scan your code now

Source: NVD / NIST