CVE-2025-40907: FCGI versions 0.44 through 0.82, for Perl, include a vulnerable version of the FastCGI fcgi2 (aka fcgi) library

Severity: medium (CVSS 5.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.7% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2025-05-16 · updated 2026-06-17
Weakness: CWE-122

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.

Affected products

FastCGI fcgi: from 0.44 through 0.82

References

http://www.openwall.com/lists/oss-security/2025/04/23/4
https://github.com/FastCGI-Archives/fcgi2/issues/67
https://github.com/FastCGI-Archives/fcgi2/releases/tag/2.4.5
https://github.com/perl-catalyst/FCGI/issues/14
https://patch-diff.githubusercontent.com/raw/FastCGI-Archives/fcgi2/pull/74.patch
https://www.synacktiv.com/en/publications/cve-2025-23016-exploiting-the-fastcgi-library

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