CVE-2012-1823
CVE-2012-1823 is a security flaw in PHP, the programming language behind many websites. Attackers can run their own code on PHP. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 25 Mar 2022.[1]
PHP is business software or equipment. Most families won’t have it, but attackers break into it to get inside companies, and from there to what those companies hold about their customers, patients and staff. PHP has published a fix or advice.
Description
CISA calls it a PHP-CGI query string parameter in PHP PHP. In its words: “sapi/cgi/cgi_main.c in PHP, when configured as a CGI script, does not properly handle query strings, which allows remote attackers to execute arbitrary code.”[1]
The CVE record adds: “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.”[2]
The underlying weakness is improper input validation (CWE-20), in MITRE’s list of common software weaknesses.
It scores 9.8 out of 10 on the Common Vulnerability Scoring System, which rates it critical, scored by the organisation that published the CVE using CVSS 3.1.[2]
Affected versions
NVD’s record doesn’t list version ranges for it; PHP’s advisory has them[3]. CISA names the product as PHP PHP.
Most families won’t have PHP; it’s for whoever looks after IT at work.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 25 Mar 2022, 3,605 days after it was made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 15 Apr 2022 to fix it.[1]
FIRST’s Exploit Prediction Scoring System, which estimates how likely a flaw is to be used in attacks in the next 30 days from what it sees across the internet, puts it at over 99%. That’s in the top 1% of the flaws it scores.[4]
CISA assesses it as automatable: attackers can run it against many targets at once.
CISA doesn’t say who was attacked, or how.
Fix
PHP has published a fix or advice.[3] CISA’s required action: “Apply updates per vendor instructions.”[1]
- Check whether you use it.PHP is business software or equipment, so most families won’t have it. If you run a business, or work from home on company equipment, ask whoever looks after your IT.
- Send this page to your IT person.Ask them to confirm it’s fixed, or not in use. CISA gave US government agencies until 15 Apr 2022 to fix it.
- If it can’t be fixed, take it offline.CISA’s advice when there’s no fix is to stop using the product, or take it off the internet, until there is one.
You can’t fix someone else’s server, but you can watch for what follows a break-in like this: a breach notice, a password reset you didn’t ask for, or a scam message that knows things it shouldn’t. HARD watches for those for you and your family.
Timeline
| Date | Event |
|---|---|
| The flaw is made public in the National Vulnerability Database, with a severity score of 9.8.[2] | |
| CISA adds it to its catalog of flaws known to be used in attacks.[1] | |
| CISA’s deadline for US government agencies to fix it.[1] | |
| FIRST puts the odds of it being used in attacks in the next 30 days at over 99%.[4] |
See also
Other PHP flaws
- CVE-2016-10033, PHPMailer: command injection ·
- CVE-2019-11043, PHP FastCGI Process Manager (FPM): buffer overflow ·
Other improper input validation flaws
- CVE-2026-93952, Arista VeloCloud Orchestrator: improper input validation ·
- CVE-2019-1068, Microsoft SQL Server: remote code execution ·
- CVE-2026-12569, PTC Windchill and FlexPLM: improper input validation ·
- CVE-2026-34910, Ubiquiti UniFi OS: improper input validation ·
- CVE-2026-6973, Ivanti Endpoint Manager Mobile (EPMM): improper input validation ·
Added the same day
- CVE-2022-26318, WatchGuard Firebox and XTM Appliances: arbitrary code execution ·
- CVE-2022-26143, Mitel MiCollab, MiVoice Business Express: access control ·
- CVE-2022-21999, Microsoft Windows: print spooler privilege escalation ·
- CVE-2021-42237, Sitecore XP: remote command execution ·
- CVE-2021-22941, Citrix ShareFile: improper access control ·
Every PHP flaw on CISA’s list · Everything added in March 2022
References
- ^ Cybersecurity and Infrastructure Security Agency. “PHP-CGI Query String Parameter Vulnerability”. Known Exploited Vulnerabilities Catalog, added 25 Mar 2022.
- ^ National Institute of Standards and Technology. “CVE-2012-1823 Detail”. National Vulnerability Database, published 11 May 2012.
- ^ PHP. Advisories and fixes: bugs.php.net, lists.fedoraproject.org, lists.fedoraproject.org, lists.fedoraproject.org.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 1.000, percentile 100.0, 31 Oct 2026.
- CVE Program. “CVE-2012-1823”. The official CVE record.
This article is built from CISA’s catalog (version 2026.10.30), NVD’s record and FIRST’s scores, kept in HARD’s database and checked every morning. The plain English is HARD’s.