CVE-2025-8033: firefox Null Dereference — Fix

Description

The JavaScript engine did not handle closed generators correctly and it was possible to resume them leading to a nullptr deref. This vulnerability was fixed in Firefox 141, Firefox ESR 115.26, Firefox ESR 128.13, Firefox ESR 140.1, Thunderbird 141, Thunderbird 128.13, and Thunderbird 140.1.

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CVSS v3.1 Score

6.5

MEDIUM

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

Weakness Type (CWE)

CWE-476 CWE-476

Affected Products

Vendor	Product	Versions
mozilla	firefox	< 115.26.0
mozilla	firefox	< 141.0
mozilla	firefox	128.0 — 128.13.0
mozilla	firefox	140.0 — 140.1.0
mozilla	thunderbird	< 128.13.0
mozilla	thunderbird	< 141.0
mozilla	thunderbird	140.0 — 140.1.0

References

Advisories & Patches

https://www.mozilla.org/security/advisories/mfsa2025-56/ https://www.mozilla.org/security/advisories/mfsa2025-57/ https://www.mozilla.org/security/advisories/mfsa2025-58/ https://www.mozilla.org/security/advisories/mfsa2025-59/ https://www.mozilla.org/security/advisories/mfsa2025-61/ https://www.mozilla.org/security/advisories/mfsa2025-62/ https://www.mozilla.org/security/advisories/mfsa2025-63/

Other References

https://bugzilla.mozilla.org/show_bug.cgi?id=1973990 https://lists.debian.org/debian-lts-announce/2025/07/msg00016.html

Frequently Asked Questions

What is CVE-2025-8033? +

The JavaScript engine did not handle closed generators correctly and it was possible to resume them leading to a nullptr deref. This vulnerability was fixed in Firefox 141, Firefox ESR 115.26, Firefox ESR 128.13, Firefox ESR 140.1, Thunderbird 141, Thunderbird 128.13, and Thunderbird 140.1. It has a CVSS v3.1 base score of 6.5 (MEDIUM).

How severe is CVE-2025-8033? +

CVE-2025-8033 has a CVSS v3.1 score of 6.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2025-8033? +

CVE-2025-8033 affects products from mozilla, specifically: firefox, thunderbird. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-8033? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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