# CVE-2013-4566: Auth bypass in n/a

> Remote attackers can bypass intended access restrictions in mod_nss when server-level client verification is disabled but directory-level verification is enabled.

- **Severity:** Medium 4.0 (`AV:N/AC:H/Au:N/C:P/I:P/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 12 Dec 2013
- **Updated:** 6 Aug 2024
- **Also known as:** GHSA-c4hv-94wj-93p7, MGASA-2013-0381, RHSA-2013:1779, SUSE-RU-2015:0591-1, UBUNTU-CVE-2013-4566

## What is CVE-2013-4566?

CVE-2013-4566 is a medium-severity authentication bypass vulnerability in Redhat Enterprise Linux, published on 12 Dec 2013. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

mod_nss 1.0.8 and earlier, when NSSVerifyClient is set to none for the server/vhost context, does not enforce the NSSVerifyClient setting in the directory context, which allows remote attackers to bypass intended access restrictions.

Weakness: CWE-264

## Which versions are affected by CVE-2013-4566?

It affects 2 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `mod_nss` | Red Hat:enterprise_linux:5::client | All versions | 0:1.0.8-8.el5_10 |
| `mod_nss-debuginfo` | Red Hat:enterprise_linux:5::client | All versions | 0:1.0.8-8.el5_10 |
| `mod_nss` | Red Hat:enterprise_linux:5::server | All versions | 0:1.0.8-8.el5_10 |
| `mod_nss-debuginfo` | Red Hat:enterprise_linux:5::server | All versions | 0:1.0.8-8.el5_10 |
| `mod_nss` | Red Hat:enterprise_linux:6::client | All versions | 0:1.0.8-19.el6_5 |
| `mod_nss-debuginfo` | Red Hat:enterprise_linux:6::client | All versions | 0:1.0.8-19.el6_5 |
| `mod_nss` | Red Hat:enterprise_linux:6::computenode | All versions | 0:1.0.8-19.el6_5 |
| `mod_nss-debuginfo` | Red Hat:enterprise_linux:6::computenode | All versions | 0:1.0.8-19.el6_5 |
| `mod_nss` | Red Hat:enterprise_linux:6::server | All versions | 0:1.0.8-19.el6_5 |
| `mod_nss-debuginfo` | Red Hat:enterprise_linux:6::server | All versions | 0:1.0.8-19.el6_5 |
| `mod_nss` | Red Hat:enterprise_linux:6::workstation | All versions | 0:1.0.8-19.el6_5 |
| `mod_nss-debuginfo` | Red Hat:enterprise_linux:6::workstation | All versions | 0:1.0.8-19.el6_5 |

Products: Mod Nss Project Mod Nss, Redhat Enterprise Linux.

## How do I fix CVE-2013-4566?

Apply the vendor's patch.

## Is CVE-2013-4566 being exploited?

There is no known exploitation of CVE-2013-4566 in the wild and no public exploit code.

## Other vulnerabilities in Redhat Enterprise Linux

- [CVE-2011-4973](https://insights.sbomify.com/CVE-2011-4973/): Auth bypass in n/a (critical 9.8)
- [CVE-2015-5244](https://insights.sbomify.com/CVE-2015-5244/): Security feature bypass in n/a (critical 9.8)
- [CVE-2015-3277](https://insights.sbomify.com/CVE-2015-3277/): Information disclosure in n/a (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2013-4566 and fix it if it is affected.

What it is: CVE-2013-4566 is a medium-severity authentication bypass vulnerability in Redhat Enterprise Linux, published on 12 Dec 2013. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2013-4566 in the wild and no public exploit code.

Affected product: Redhat Enterprise Linux. 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-2013-4566/ (Markdown: https://insights.sbomify.com/CVE-2013-4566/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2013-4566
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2013-4566
- OSV: https://osv.dev/vulnerability/CVE-2013-4566

---
From sbomify Insights: https://insights.sbomify.com/CVE-2013-4566/
Summaries are generated and may contain mistakes; the official description above is the record.