# CVE-2004-0189: Security feature bypass in n/a

> Remote attackers can bypass URL access control lists in Squid proxy servers by using NULL characters in URLs, allowing unauthorized access to restricted resources.

- **Severity:** High 7.5 (`AV:N/AC:L/Au:N/C:P/I:P/A:P`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 1 Sep 2004
- **Updated:** 8 Aug 2024
- **Also known as:** DEBIAN-CVE-2004-0189, DSA-474, GHSA-wgp5-p97p-cph9, RHSA-2004:133

## What is CVE-2004-0189?

CVE-2004-0189 is a high-severity vulnerability in n/a, published on 1 Sep 2004. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

## Which versions are affected by CVE-2004-0189?

It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `squid` | Red Hat:enterprise_linux:3::as | All versions | 7:2.5.STABLE3-5.3E |
| `squid-debuginfo` | Red Hat:enterprise_linux:3::as | All versions | 7:2.5.STABLE3-5.3E |
| `squid` | Red Hat:enterprise_linux:3::desktop | All versions | 7:2.5.STABLE3-5.3E |
| `squid-debuginfo` | Red Hat:enterprise_linux:3::desktop | All versions | 7:2.5.STABLE3-5.3E |
| `squid` | Red Hat:enterprise_linux:3::es | All versions | 7:2.5.STABLE3-5.3E |
| `squid-debuginfo` | Red Hat:enterprise_linux:3::es | All versions | 7:2.5.STABLE3-5.3E |
| `squid` | Red Hat:enterprise_linux:3::ws | All versions | 7:2.5.STABLE3-5.3E |
| `squid-debuginfo` | Red Hat:enterprise_linux:3::ws | All versions | 7:2.5.STABLE3-5.3E |

Products: Squid Squid.

## How do I fix CVE-2004-0189?

Upgrade to a fixed version.

## Is CVE-2004-0189 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2004-0189 exists.

Public exploit code:

- Squid Proxy 2.4/2.5 - NULL URL Character Unauthorized Access (exploitdb)

## Other vulnerabilities in n/a

- [CVE-2005-0194](https://insights.sbomify.com/CVE-2005-0194/): Auth bypass in n/a (critical 10.0)
- [CVE-2005-1345](https://insights.sbomify.com/CVE-2005-1345/): Missing authorization in n/a (high 7.5)
- [CVE-2005-0173](https://insights.sbomify.com/CVE-2005-0173/): Auth bypass in n/a (high 7.5)
- [CVE-2002-0163](https://insights.sbomify.com/CVE-2002-0163/): Memory corruption in n/a (high 7.5)
- [CVE-2002-0714](https://insights.sbomify.com/CVE-2002-0714/): Security feature bypass in n/a (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2004-0189 and fix it if it is affected.

What it is: CVE-2004-0189 is a high-severity vulnerability in n/a, published on 1 Sep 2004. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2004-0189 exists.

Affected product: n/a. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2004-0189/ (Markdown: https://insights.sbomify.com/CVE-2004-0189/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2004-0189
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2004-0189
- OSV: https://osv.dev/vulnerability/CVE-2004-0189

---
From sbomify Insights: https://insights.sbomify.com/CVE-2004-0189/
Summaries are generated and may contain mistakes; the official description above is the record.