# CVE-2021-39275: ap_escape_quotes buffer overflow

> A buffer overflow in ap_escape_quotes allows attackers to cause denial of service or execute arbitrary code via malicious input in third-party modules.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 16 Sep 2021
- **Updated:** 4 Aug 2024
- **Also known as:** ALPINE-CVE-2021-39275, AZL-6486, BIT-apache-2021-39275, CLEANSTART-2026-OA19961, CLSA-2021-1634745216, CLSA-2021-1634922666, CVE-2022-21384, DEBIAN-CVE-2021-39275, GHSA-p59c-pqfv-4fwc, OESA-2021-1387, SUSE-SU-2021:14811-1, UBUNTU-CVE-2021-39275

## What is CVE-2021-39275?

CVE-2021-39275 is a critical memory corruption vulnerability in Apache Http Server, published on 16 Sep 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

ap_escape_quotes() may write beyond the end of a buffer when given malicious input. No included modules pass untrusted data to these functions, but third-party / external modules may. This issue affects Apache HTTP Server 2.4.48 and earlier.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2021-39275?

1 open source package ship an affected version, including apache. It affects 11 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `apache` | Bitnami | All versions | 2.4.49 |
| `apache2` | SUSE:Linux Enterprise Point of Sale 11 SP3 | All versions | 2.2.34-70.38.1 |
| `apache2` | SUSE:Linux Enterprise Server 11 SP4-LTSS | All versions | 2.2.34-70.38.1 |

Products: Apache Http Server, Debian Debian Linux, Fedoraproject Fedora, Netapp Cloud Backup, Netapp Clustered Data Ontap, Netapp Storagegrid, Oracle Http Server, Oracle Instantis Enterprisetrack, Oracle Zfs Storage Appliance Kit, Siemens Sinec Nms, Siemens Sinema Server.

## How do I fix CVE-2021-39275?

Upgrade apache to 2.4.49 or later.

## Is CVE-2021-39275 being exploited?

There is no known exploitation of CVE-2021-39275 in the wild and no public exploit code.

## 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-2021-39275 and fix it if it is affected.

What it is: CVE-2021-39275 is a critical memory corruption vulnerability in Apache Http Server, published on 16 Sep 2021. 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-2021-39275 in the wild and no public exploit code.

Affected packages and fixed versions:
- apache (Bitnami): affected all versions; fixed in 2.4.49

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-2021-39275/ (Markdown: https://insights.sbomify.com/CVE-2021-39275/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-39275
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-39275
- OSV: https://osv.dev/vulnerability/CVE-2021-39275

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-39275/
Summaries are generated and may contain mistakes; the official description above is the record.