# CVE-2011-4415: Denial of service in n/a

> Local attackers can cause denial of service via crafted .htaccess files and HTTP headers when mod_setenvif is enabled.

- **Severity:** Low 1.2 (`AV:L/AC:H/Au:N/C:N/I:N/A:P`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 8 Nov 2011
- **Updated:** 7 Aug 2024
- **Also known as:** DEBIAN-CVE-2011-4415, GHSA-43r8-mvrp-6q9c

## What is CVE-2011-4415?

CVE-2011-4415 is a low-severity denial of service vulnerability in Apache Http Server, published on 8 Nov 2011. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

The ap_pregsub function in server/util.c in the Apache HTTP Server 2.0.x through 2.0.64 and 2.2.x through 2.2.21, when the mod_setenvif module is enabled, does not restrict the size of values of environment variables, which allows local users to cause a denial of service (memory consumption or NULL pointer dereference) via a .htaccess file with a crafted SetEnvIf directive, in conjunction with a crafted HTTP request header, related to (1) the "len +=" statement and (2) the apr_pcalloc function call, a different vulnerability than CVE-2011-3607.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2011-4415?

It affects 1 product.


Products: Apache Http Server.

## How do I fix CVE-2011-4415?

Upgrade to a fixed version.

## Is CVE-2011-4415 being exploited?

There is no known exploitation of CVE-2011-4415 in the wild and no public exploit code.

Public exploit code:

- Apache < 2.0.64 / < 2.2.21 mod_setenvif - Integer Overflow (exploitdb)

## Other vulnerabilities in Apache Http Server

- [CVE-2021-42013](https://insights.sbomify.com/CVE-2021-42013/): Apache HTTP Server Path Traversal (critical 9.8, exploited in the wild)
- [CVE-2024-38475](https://insights.sbomify.com/CVE-2024-38475/): Apache HTTP Server Improper Escaping of Output (critical 9.1, exploited in the wild)
- [CVE-2021-40438](https://insights.sbomify.com/CVE-2021-40438/): Apache HTTP Server-Side Request Forgery (SSRF) (critical 9.0, exploited in the wild)
- [CVE-2019-0211](https://insights.sbomify.com/CVE-2019-0211/): Apache HTTP Server Privilege Escalation (high 7.8, exploited in the wild)
- [CVE-2021-41773](https://insights.sbomify.com/CVE-2021-41773/): Apache HTTP Server Path Traversal (high 7.5, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2011-4415 and fix it if it is affected.

What it is: CVE-2011-4415 is a low-severity denial of service vulnerability in Apache Http Server, published on 8 Nov 2011. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2011-4415 in the wild and no public exploit code.

Affected product: Apache Http Server. 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-2011-4415/ (Markdown: https://insights.sbomify.com/CVE-2011-4415/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2011-4415
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2011-4415
- OSV: https://osv.dev/vulnerability/CVE-2011-4415

---
From sbomify Insights: https://insights.sbomify.com/CVE-2011-4415/
Summaries are generated and may contain mistakes; the official description above is the record.