CVE-2025-1943: firefox Heap Overflow — Fix

Description

Memory safety bugs present in Firefox 135 and Thunderbird 135. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 136 and Thunderbird 136.

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CVSS v3.1 Score

8.2

HIGH

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

Weakness Type (CWE)

CWE-122 CWE-122

Affected Products

Vendor	Product	Versions
mozilla	firefox	< 136.0
mozilla	thunderbird	< 136.0

References

Advisories & Patches

https://www.mozilla.org/security/advisories/mfsa2025-14/ https://www.mozilla.org/security/advisories/mfsa2025-17/

Other References

https://bugzilla.mozilla.org/buglist.cgi?bug_id=1869650%2C1938451%2C1940326%2C1944052%2C1944063%2C1947281

Frequently Asked Questions

What is CVE-2025-1943? +

Memory safety bugs present in Firefox 135 and Thunderbird 135. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 136 and Thunderbird 136. It has a CVSS v3.1 base score of 8.2 (HIGH).

How severe is CVE-2025-1943? +

CVE-2025-1943 has a CVSS v3.1 score of 8.2 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching.

What products are affected by CVE-2025-1943? +

CVE-2025-1943 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-2025-1943? +

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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CVE-2025-1943