CVE-2012-2311: sapi/cgi/cgi_main.c in PHP before 5.3.13 and 5.4.x before 5.4.3, when configured as a CGI script (aka php-cgi), does…

Is it exploited?

Reported, not confirmed by CISA. VulnCheck KEV lists it as exploited in the wild. CISA has not added it to its Known Exploited Vulnerabilities catalog as of 29 Oct 2026.

VulnCheck KEV lists it since 9 May 2012. It cites 3 public reports, the first from 9 May 2012.

• blog.sucuri.net
• fortiguard.com
• bleepingcomputer.com

How likely is exploitation in the next 30 days?

69.3%

EPSS score, percentile 99.4 of all scored records. A probability estimated by FIRST, not a report of exploitation.

How severe?

Not scored

The CVE record carries no CVSS score.

What should I do?

CISA has set no required action, because the vulnerability is not in KEV.

Advisories and patches (7)

Which versions are affected?

Not stated. The CVE record gives vendor and product as “n/a” and the version as “unspecified”.

Source: CISA KEV 2026.10.29, as of 29 Oct 2026; VulnCheck KEV, as of 30 Oct 2026; FIRST EPSS, as of 29 Oct 2026; CVE List, as of 30 Oct 2026. About the data.

Description

sapi/cgi/cgi_main.c in PHP before 5.3.13 and 5.4.x before 5.4.3, when configured as a CGI script (aka php-cgi), does not properly handle query strings that contain a %3D sequence but no = (equals sign) character, which allows remote attackers to execute arbitrary code by placing command-line options in the query string, related to lack of skipping a certain php_getopt for the 'd' case. NOTE: this vulnerability exists because of an incomplete fix for CVE-2012-1823.

Source: CVE List, as of 30 Oct 2026. About the data.

What to do

Advisories and patches

• SSRT100856 (Vendor advisory)
• SUSE-SU-2012:0604 (Vendor advisory)
• openSUSE-SU-2012:0590 (Vendor advisory)
• SUSE-SU-2012:0598 (Vendor advisory)
• APPLE-SA-2012-09-19-2 (Vendor advisory)
• SSRT100992 (Vendor advisory)
• DSA-2465 (Vendor advisory)

This summary is based on the CVE record as of 30 Oct 2026. Check the vendor's advisory before you act: affected versions and fixes can change.

Affected products and versions

The CVE record does not name affected products or versions: vendor and product are “n/a” and the version is “unspecified”.

Source: CVE List, as of 30 Oct 2026. About the data.

Timeline