# CVE-2026-50269: AIOHTTP: CRLF injection in multipart headers


- **Severity:** Low 2.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 22 Jun 2026
- **Updated:** 22 Jun 2026
- **Also known as:** AZL-90656, CLEANSTART-2026-NU42168, CLEANSTART-2026-OD07469, DEBIAN-CVE-2026-50269, ECHO-b9f2-2c14-64ab, GHSA-m6qw-4cw2-hm4m, MINI-2374-p395-c8gp, MINI-28cc-vf5v-6hvf, MINI-3fv5-jmpv-vq4f, MINI-6cvj-xw49-q9vf, MINI-6rc7-pcx5-6qpq, MINI-89jq-hg65-95qx, MINI-g4w5-4g88-28q2, MINI-g7xg-hpq8-r65p, MINI-gvj4-5qg5-4cf2, MINI-hcwf-4jcx-9pr4, MINI-mjgm-9hc9-h5gq, MINI-p69x-qp3p-q2cc, MINI-pf2v-973c-7mh3, MINI-q44c-63h3-6x2x, MINI-r438-83m7-mc5f, MINI-vq4x-wr2m-j2jw, PYSEC-2026-2106, ROOT-APP-PYPI-CVE-2026-50269, UBUNTU-CVE-2026-50269

## What is CVE-2026-50269?

CVE-2026-50269 is a low-severity vulnerability in aio-libs aiohttp, published on 22 Jun 2026. 

### Official description

AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.0, attacker-controlled input included into multipart/payload headers can be used to modify a request to inject additional headers or similar. In the unlikely situation that an application is passing user-controlled strings into MultipartWriter.append(headers=...) or Payload.headers, then an attacker may be able to modify the request to inject headers or change the contents of the request. This vulnerability is fixed in 3.14.0.

Weakness: CWE-93 (Improper Neutralization of CRLF Sequences), CWE-113 (Improper Neutralization of CRLF Sequences in HTTP Headers)

## Which versions are affected by CVE-2026-50269?

3 open source packages ship an affected version, including aiohttp. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `aiohttp` | PyPI | All versions | 3.14.0 |
| `aiohttp` | PyPI | All versions | 3.14.0 |
| `aiohttp` | PyPI | All versions | 3.14.0 |

Products: Aiohttp Aiohttp.

## How do I fix CVE-2026-50269?

Upgrade aiohttp to 3.14.0 or later.

## Is CVE-2026-50269 being exploited?

There is no known exploitation of CVE-2026-50269 in the wild and no public exploit code.

## Other vulnerabilities in aio-libs aiohttp

- [CVE-2024-52303](https://insights.sbomify.com/CVE-2024-52303/): aiohttp memory leak when middleware is enabled when requesting a resource with a non-allowed method (high 8.7)
- [CVE-2025-69223](https://insights.sbomify.com/CVE-2025-69223/): AIOHTTP's HTTP Parser auto_decompress feature is vulnerable to zip bomb (high 7.5)
- [CVE-2024-30251](https://insights.sbomify.com/CVE-2024-30251/): Denial of service when trying to parse malformed POST requests in aiohttp (high 7.5)
- [CVE-2023-49081](https://insights.sbomify.com/CVE-2023-49081/): aiohttp's ClientSession is vulnerable to CRLF injection via version (high 7.2)
- [CVE-2026-22815](https://insights.sbomify.com/CVE-2026-22815/): AIOHTTP: Uncapped memory usage possible through aiohttp allowing unlimited trailer headers (medium 6.9)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-50269 and fix it if it is affected.

What it is: CVE-2026-50269 is a low-severity vulnerability in aio-libs aiohttp, published on 22 Jun 2026. 
Exploitation: There is no known exploitation of CVE-2026-50269 in the wild and no public exploit code.

Affected packages and fixed versions:
- aiohttp (PyPI): affected all versions; fixed in 3.14.0
- aiohttp (PyPI): affected all versions; fixed in 3.14.0
- aiohttp (PyPI): affected all versions; fixed in 3.14.0

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-2026-50269/ (Markdown: https://insights.sbomify.com/CVE-2026-50269/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-50269
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-50269
- OSV: https://osv.dev/vulnerability/CVE-2026-50269

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-50269/
Summaries are generated and may contain mistakes; the official description above is the record.