# CVE-2011-2581: Security feature bypass in n/a

> Remote attackers can bypass access restrictions on Cisco Nexus switches by exploiting improper handling of ACL comments in deny statements.

- **Severity:** Medium 5.0 (`AV:N/AC:L/Au:N/C:P/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 14 Sep 2011
- **Updated:** 6 Aug 2024
- **Also known as:** GHSA-c76p-58cp-48fg

## What is CVE-2011-2581?

CVE-2011-2581 is a medium-severity vulnerability in Cisco Nx-Os, published on 14 Sep 2011. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The ACL implementation in Cisco NX-OS 5.0(2) and 5.0(3) before 5.0(3)N2(1) on Nexus 5000 series switches, and NX-OS before 5.0(3)U1(2a) on Nexus 3000 series switches, does not properly handle comments in conjunction with deny statements, which allows remote attackers to bypass intended access restrictions in opportunistic circumstances by sending packets, aka Bug IDs CSCto09813 and CSCtr61490.

Weakness: CWE-264

## Which versions are affected by CVE-2011-2581?

It affects 3 products.


Products: Cisco Nexus 3000, Cisco Nexus 5000, Cisco Nx-Os.

## How do I fix CVE-2011-2581?

No fix has been published for CVE-2011-2581 yet. Limit exposure of the affected software until one is available.

## Is CVE-2011-2581 being exploited?

There is no known exploitation of CVE-2011-2581 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2011-2581 and fix it if it is affected.

What it is: CVE-2011-2581 is a medium-severity vulnerability in Cisco Nx-Os, published on 14 Sep 2011. 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-2011-2581 in the wild and no public exploit code.

Affected product: Cisco Nx-Os. 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-2011-2581/ (Markdown: https://insights.sbomify.com/CVE-2011-2581/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2011-2581
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2011-2581
- OSV: https://osv.dev/vulnerability/CVE-2011-2581

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From sbomify Insights: https://insights.sbomify.com/CVE-2011-2581/
Summaries are generated and may contain mistakes; the official description above is the record.