CVE-2025-40907

Name: CVE-2025-40907
Creator: NVD / NIST
Published: 2025-05-16T13:15:52.683+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.3/10EPSS 0.52%

Last modified Jun 17, 2026

CVE-2025-40907 is a medium-severity vulnerability rated 5.3/10 on the CVSS scale. FCGI versions 0.44 through 0.82, for Perl, include a vulnerable version of the FastCGI fcgi2 (aka fcgi) library. The included FastCGI library is affected by CVE-2025-23016, causing an integer overflow (and resultant heap-based buffer overflow) via crafted nameLen or valueLen values in data to the IPC socket. This occurs in ReadParams in fcgiapp.c.. EPSS estimates a 0.52% chance of exploitation in the next 30 days.

Description

FCGI versions 0.44 through 0.82, for Perl, include a vulnerable version of the FastCGI fcgi2 (aka fcgi) library. The included FastCGI library is affected by CVE-2025-23016, causing an integer overflow (and resultant heap-based buffer overflow) via crafted nameLen or valueLen values in data to the IPC socket. This occurs in ReadParams in fcgiapp.c.

Metrics

CVSS 3.1

5.3/10

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

EPSS Probability

0.52%

39.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Fastcgi	Fcgi	>= 0.44, <= 0.82

References

http://www.openwall.com/lists/oss-security/2025/04/23/4Mailing List, Third Party Advisory
https://github.com/FastCGI-Archives/fcgi2/issues/67Exploit, Issue Tracking
https://github.com/FastCGI-Archives/fcgi2/releases/tag/2.4.5Release Notes
https://github.com/perl-catalyst/FCGI/issues/14Exploit, Issue Tracking
https://patch-diff.githubusercontent.com/raw/FastCGI-Archives/fcgi2/pull/74.patchPatch
https://www.synacktiv.com/en/publications/cve-2025-23016-exploiting-the-fastcgi-libraryExploit, Third Party Advisory

Timeline

Published: May 16, 2025
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2025-40907?

How severe is CVE-2025-40907?

CVE-2025-40907 has a CVSS score of 5.3/10 (MEDIUM severity). The EPSS model estimates a 0.52% probability of exploitation in the next 30 days.

How do I fix CVE-2025-40907?

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-2025-40907?

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

Scan your code now

Source: NVD / NIST