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CVE-2004-0189· NVD / CVE Program· CNA mitre

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

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.

HighCVSS 7.5 · v2.0—Proof of concept Fix available
Published
Mar 15, 2004
Updated
Jun 16, 2026
EPSS
13.8% · 96th percentile
CWE
—
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Report tools

JSON

Action score

34

Monitor

Low priority for now.

CVSS
30 / 40 · 7.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
4 / 30 · 13.8%

Affected systems

VendorProduct
squidsquid

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • squid squid2.0_patch2
  • squid squid2.1_patch2
  • squid squid2.3_stable5
  • squid squid2.4
  • squid squid2.4_stable7
  • squid squid2.5_stable3
  • squid squid2.5_stable4

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12squidbefore 2.5.5-12.5.5-1
Debian:3.0squidbefore 2.4.6-2woody22.4.6-2woody2
Red Hat:enterprise_linux:3::assquidbefore 7:2.5.STABLE3-5.3E7:2.5.STABLE3-5.3E
Red Hat:enterprise_linux:3::assquid-debuginfobefore 7:2.5.STABLE3-5.3E7:2.5.STABLE3-5.3E

Same product

squid: all records

Other highest-scoring records for the same primary product.

  • CVE-2009-0478Squid 2.7 to 2.7.STABLE5, 3.0 to 3.0.STABLE12, and 3.1 to 3.1.0.4 allows remote attackers to cause a denial of service via an HTTP request w
    42Plan
  • CVE-2005-0194Squid 2.5, when processing the configuration file, parses empty Access Control Lists (ACLs), including proxy_auth ACLs without defined auth
    42Plan
  • CVE-2005-0241The httpProcessReplyHeader function in http.c for Squid 2.5-STABLE7 and earlier does not properly set the debug context when it is handling
    41Plan
  • CVE-2005-0095The WCCP message parsing code in Squid 2.5.STABLE7 and earlier allows remote attackers to cause a denial of service (crash) via malformed WC
    41Plan
  • CVE-2005-0173squid_ldap_auth in Squid 2.5 and earlier allows remote authenticated users to bypass username-based Access Control Lists (ACLs) via a userna
    40Plan
  • CVE-2005-0174Squid 2.5 up to 2.5.STABLE7 allows remote attackers to poison the cache or conduct certain attacks via headers that do not follow the HTTP s
    35Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
debian:squid2.5.5-1 · Debian:12Package registry (OSV)
red hat:squid7:2.5.STABLE3-5.3E · Red Hat:enterprise_linux:3::asPackage registry (OSV)
red hat:squid-debuginfo7:2.5.STABLE3-5.3E · Red Hat:enterprise_linux:3::asPackage registry (OSV)

Exploit status

Proof of concept available

A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.

Evidence

  • Exploit-DB entry ×1

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
SourceKindDate
Exploit-DB entryremote2004-03-01

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. First PoC-14 d
  2. Published
  3. TodaySep 30, 2026+8234 d
EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • No special conditions are required; it is repeatable.

If successful

Confidentiality
P · data can be read
Integrity
P · data or configuration can be modified
Availability
P · the service can be disrupted
Attack complexity
Low
Confidentiality impact
P
Integrity impact
P
Availability impact
P

Weakness class (CWE)

—

CVSS vector

AV:N/AC:L/Au:N/C:P/I:P/A:P

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Noroxi analysis

No Noroxi analysis for this record yet

We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.

We use this product, ask for help

Change log

  1. Fix✗ → ✓

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References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records