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Fencer Vulns
high 7.5

CVE-2004-0189 in the critical feed json

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 ("%0…

published 2004-03-15 22 y ago modified 2026-06-16 4 mo ago also EUVD-2004-0189

cvss
7.5
version 2.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
13.8%
EPSS 13.8% chance of exploitation in 30 days, percentile 96%
public exploits
1
Exploit-DB

Summary

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.

Patch / fix

  • squid Debian 14, Debian 13, Debian 12 2.5.5-1

debian advisories DEBIAN-CVE-2004-0189

  • squid RHEL 3 7:2.5.STABLE3-5.3E

red hat advisories RHSA-2004:133

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2004-0189 updated

security flaw

  • Red Hat Desktop version 3 squid 2.5.STABLE3-5.3E Red Hat Enterprise Linux AS version 3 squid 2.5.STABLE3-5.3E Red Hat Enterprise Linux ES version 3 squid 2.5.STABLE3-5.3E Red Hat Enterprise Linux WS version 3 squid 2.5.STABLE3-5.3E
    fixed: vendor fix RHSA-2004:133
  • Red Hat Linux 9
    fixed: vendor fix RHSA-2004:134

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Timeline

  1. First public exploit (EDB-23777)
  2. Published

Exploit prediction

13.81% chance of exploitation in the next 30 days, higher than 96% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • EDB-23777 Squid Proxy 2.4/2.5 - NULL URL Character Unauthorized Access remote, 2004-03-01
  • squid-cache.org http://www.squid-cache.org/Advisories/SQUID-2004_1.txt referenced PoC, tagged "exploit" by a source, unverified
  • securityfocus.com http://www.securityfocus.com/bid/9778 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.