CVE-2025-11721

Description

Memory safety bug present in Firefox 143 and Thunderbird 143. This bug showed evidence of memory corruption and we presume that with enough effort this could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 144 and Thunderbird 144.

CVSS v3.1 Score

9.8

CRITICAL

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

Weakness Type (CWE)

CWE-119 Buffer Overflow

Affected Products

Vendor	Product	Versions
mozilla	firefox	143.0 — 144.0
mozilla	thunderbird	143.0 — 144.0

References

Advisories & Patches

https://www.mozilla.org/security/advisories/mfsa2025-81/ https://www.mozilla.org/security/advisories/mfsa2025-84/

Other References

https://bugzilla.mozilla.org/show_bug.cgi?id=1986816

Frequently Asked Questions

What is CVE-2025-11721? +

Memory safety bug present in Firefox 143 and Thunderbird 143. This bug showed evidence of memory corruption and we presume that with enough effort this could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 144 and Thunderbird 144. It has a CVSS v3.1 base score of 9.8 (CRITICAL).

How severe is CVE-2025-11721? +

CVE-2025-11721 has a CVSS v3.1 score of 9.8 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately.

What products are affected by CVE-2025-11721? +

CVE-2025-11721 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-2025-11721? +

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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