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Vulnerability record · CVE-2025-40907 · published 16 May 2025

CVE-2025-40907: Fastcgi fcgi heap-based buffer overflow vulnerability

FFastcgi · Fcgi

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.

5.3 CVSS 3.1 Medium EPSS 0.65% · top 51.0% CWE-122 · Heap-based buffer overflowCWE-190 · Integer overflow
5.3CVSS 3.1 base score
0.65%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
6References, 3 tagged exploit
17 Jun 2026Last modified by NVD

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.

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

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

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

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2025-40907), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.