How severe is CVE-2012-1823?

CVE-2012-1823 has a CVSS score of 9.8/10, rated CRITICAL. Immediate patching is strongly recommended.

Which packages are affected by CVE-2012-1823?

Affected package information for CVE-2012-1823 is not yet fully mapped. Check the official advisory links for details.

How do I fix CVE-2012-1823?

No fixed release is recorded for CVE-2012-1823 yet. Track the upstream advisory, and apply the exposure-reduction steps below in the meantime.

How do I detect CVE-2012-1823 in my code and dependencies?

Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`).

How do I mitigate CVE-2012-1823 if there is no patch (or I can't update yet)?

Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.

Is CVE-2012-1823 actively exploited in the wild?

Yes. There are 18 known exploit references for CVE-2012-1823, including 4 documented proof-of-concept exploits on Exploit-DB and 11 in-the-wild exploitations observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2012-1823?

CVE-2012-1823 has an EPSS (Exploit Prediction Scoring System) score of 100.0%, placing it in the 100th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. A score above 50% indicates significantly elevated exploitation risk — immediate patching is strongly recommended.

Is CVE-2012-1823 in the CISA Known Exploited Vulnerabilities catalog?

Yes. CVE-2012-1823 (PHP-CGI Query String Parameter Vulnerability) was added to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2022-03-25. CISA required all US federal civilian agencies to remediate this vulnerability by 2022-04-15. The required action was: Apply updates per vendor instructions. Being listed in the KEV catalog is the strongest possible confirmation of active exploitation — treat this as a critical priority.

What type of vulnerability is CVE-2012-1823?

CVE-2012-1823 is classified as CWE-77 (CWE-77). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

Is there exploit tooling available for CVE-2012-1823?

A Nuclei detection template exists for CVE-2012-1823, meaning automated scanners can fingerprint it. Public exploit tooling significantly increases real-world risk — prioritize patching and ensure detection coverage. Exploit tooling should only ever be used in isolated, authorized testing environments.

When was CVE-2012-1823 published, and has it been updated?

CVE-2012-1823 was published on May 11, 2012 and was last updated on November 4, 2025. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🛡️

CISA KEV · ACTIVELY EXPLOITED

CRITICAL severity

CVE-2012-1823 — Red Hat

CRITICAL

CVE-2012-1823 is a critical-severity (CVSS 9.8) CWE-77 vulnerability. It is in CISA's Known Exploited Vulnerabilities catalog (added 2022-03-25) — treat it as actively exploited and patch now. No vendor fix is recorded yet; mitigation options are listed below.

sapi/cgi/cgi_main.c in PHP before 5.3.12 and 5.4.x before 5.4.2, when configured as a CGI script (aka php-cgi), does not properly handle query strings that lack an = (equals sign) character,…

Published

May 11, 2012

Updated

Nov 4, 2025

Affected

17 products

Patched

See advisory

Exploits

18 known

Exploitation data as of Oct 22, 2026 · OSV.dev, NVD, CISA KEV, FIRST.org (EPSS)

Exploitation Status

Actively exploited in the wild

Confirmed by CISA's Known Exploited Vulnerabilities catalog on 2022-03-25. Federal agencies were required to remediate by 2022-04-15.
CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
A successful exploit gives an attacker total control of the affected component, not partial access.

Exploitation and automatability from CISA (KEV catalog and SSVC triage) for CVE-2012-1823.

EPSS Exploitation Probability

via FIRST.org ↗

100.0%probability of exploitation in next 30 days

Very High Risk0.00%

Lower risk than most CVEs100th percentile — riskier than 100% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2012-1823 by exploitation likelihood (EPSS) against impact (CVSS). In the shaded patch-first corner (EPSS 50%+, CVSS 7.0+).

Where this sits among everything scored

Of 395,249 CVEs with a current EPSS score, this one falls in the ≥ 90% band (highlighted). Counts from FIRST.org, log-scaled.

Description

sapi/cgi/cgi_main.c in PHP before 5.3.12 and 5.4.x before 5.4.2, when configured as a CGI script (aka php-cgi), does not properly handle query strings that lack an = (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.

Affected Products

17 products · 30 configurations

mac os xapple

≥ 10.8.0 && < 10.8.2

range

debian linuxdebian

1 version

6.0

fedorafedoraproject

2 versions

3940

hp-uxhp

2 versions

b.11.23b.11.31

opensuseopensuse

2 versions

11.412.1

Application

phpphp

≥ 5.4.0 && < 5.4.2

range

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

EDB-29290remotephp✓ Verified

Apache + PHP < 5.3.12 / < 5.4.2 - cgi-bin Remote Code Execution

by kingcope · Oct 29, 2013

Exploit-DB Source

EDB-29316remotephp

Apache + PHP < 5.3.12 / < 5.4.2 - Remote Code Execution + Scanner

by noptrix · Oct 31, 2013

Exploit-DB Source

EDB-18836remotephp✓ Verified

PHP < 5.3.12 / < 5.4.2 - CGI Argument Injection

by rayh4c · May 5, 2012

Exploit-DB Source

EDB-18834remotephp✓ Verified

PHP 5.3.12/5.4.2 - CGI Argument Injection (Metasploit)

by Metasploit · May 4, 2012

Exploit-DB Source

Detection & mitigation playbook

Vulnerability

Detect
Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`).
Remediation status
No fixed release is recorded for CVE-2012-1823 yet. Track the upstream advisory, and apply the exposure-reduction steps below in the meantime.
Mitigate without a patch
Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.

How to detect CVE-2012-1823

A community-maintained Nuclei template exists for this CVE. You can scan for it directly:

nuclei -id cve-2012-1823 -u https://target

Template: PHP CGI v5.3.12/5.4.2 Remote Code Execution
Severity: high
Impact: Remote code execution
Remediation: Upgrade to a patched version of PHP or apply the necessary security patches.

Template by ProjectDiscovery nuclei-templates (pikpikcu), MIT licensed. View the full template. Scan only systems you are authorised to test.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatCritical

This flaw did not affect the versions of PHP in Red Hat Enterprise Linux 3 or 4. Updates were released for Red Hat Enterprise Linux 5 and 6 (RHSA-2012:0546, RHSA-2012:0547), Red Hat Enterprise Linux 5.3 Long Life (RHSA-2012:0568), Red Hat Enterprise Linux 5.6, 6.0, and 6.1 Extended Update Support (RHSA-2012:0568,…

Product	Fixed in	Advisory
Red Hat Enterprise Linux 5	`php-0:5.1.6-34.el5_8`	RHSA-2012:0546
Red Hat Enterprise Linux 5	`php53-0:5.3.3-7.el5_8`	RHSA-2012:0547
Red Hat Enterprise Linux 5.3 Long Life	`php-0:5.1.6-23.3.el5_3`	RHSA-2012:0568
Red Hat Enterprise Linux 5.6 EUS - Server Only	`php53-0:5.3.3-1.el5_6.2`	RHSA-2012:0569

UbuntuCRITICAL

USN-1437-1Ubuntu

Frequently Asked Questions

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CVE-2012-1823 — Red Hat

Exploitation Status

Actively exploited in the wild

EPSS Exploitation Probability

How urgent is this, really

Where this sits among everything scored

Description

Affected Products

Detection & mitigation playbook

Detect

Remediation status

Mitigate without a patch

How to detect CVE-2012-1823

Fixing This On Your OS

Frequently Asked Questions

Is CVE-2012-1823 in your dependencies?