# CVE-2026-69243: AIOHTTP: HTTP request smuggling via WebSocket upgrade

> Attackers can exploit HTTP request smuggling via WebSocket upgrades in aiohttp server, potentially leading to data manipulation or cache poisoning.

- **Severity:** Medium 6.3 (`CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 3 Aug 2026
- **Updated:** 5 Aug 2026
- **Also known as:** AZL-94547, CLEANSTART-2026-QH29600, CLSA-2026-1788935722, DEBIAN-CVE-2026-69243, ECHO-4652-b79b-c705, GHSA-mfx4-hv73-q22v, MINI-26h9-xgr4-wjhh, MINI-2vj7-jhfh-98rf, MINI-35ch-627g-3c85, MINI-3h3v-hwrc-c5xm, MINI-4q2p-5q8v-x326, MINI-55gh-3cv2-99mh, MINI-647w-vq8f-9cv6, MINI-73p9-r47g-5gr2, MINI-7q39-846j-3gr4, MINI-9g5g-p65q-68p4, MINI-9x2q-mph6-2g9g, MINI-c7g4-6mhg-m86q, MINI-c9f7-ww7c-cghx, MINI-cqcq-f4hr-c97c, MINI-crpp-5gq5-rpp5, MINI-fj3q-cr97-989f, MINI-gfq7-mphg-p9h2, MINI-h4wh-w4wq-7g2h, MINI-j295-89j2-88q4, MINI-m5c9-pjpj-jj4m, MINI-mwc6-mh3v-6r4q, MINI-p824-g6v2-v8qv, MINI-pg2m-q9c4-wh3x, MINI-q4vx-48p4-789p, MINI-qwvv-6chf-94vr, MINI-r3m9-vc4f-7fmc, MINI-vpq7-h7h4-cr8g, MINI-xph5-rmq3-xpj7, OESA-2026-3581, OESA-2026-3582, OESA-2026-3583, PYSEC-2026-3546, UBUNTU-CVE-2026-69243

## What is CVE-2026-69243?

CVE-2026-69243 is a medium-severity vulnerability in aio-libs aiohttp, published on 3 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.2, the HTTP parsers were vulnerable to a request smuggling attack relating to WebSocket upgrades. If using the server-side component, an attacker may be able to execute a request smuggling vulnerability using an edge case in the WebSocket upgrade procedure. A WebSocket upgrade request with a body could cause the parser to switch protocols before the complete request body was received, leaving trailing bytes to be handled as upgraded-protocol or pipelined data rather than normal HTTP body data. This issue is fixed in version 3.14.2.

Weakness: CWE-444 (Inconsistent Interpretation of HTTP Requests)

## Which versions are affected by CVE-2026-69243?

3 open source packages ship an affected version, including aiohttp.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `aiohttp` | PyPI | All versions | 3.14.2 |
| `aiohttp` | PyPI | All versions | 3.14.2 |
| `aiohttp` | PyPI | All versions | 3.14.2 |

## How do I fix CVE-2026-69243?

Upgrade aiohttp to 3.14.2 or later.

## Is CVE-2026-69243 being exploited?

There is no known exploitation of CVE-2026-69243 in the wild and no public exploit code.

Public exploit code:

- https://github.com/JVBotelho/cve-2026-69243-poc-aiohttp-smuggling (github_poc): https://github.com/JVBotelho/cve-2026-69243-poc-aiohttp-smuggling

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-69243 and fix it if it is affected.

What it is: CVE-2026-69243 is a medium-severity vulnerability in aio-libs aiohttp, published on 3 Aug 2026. 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-2026-69243 in the wild and no public exploit code.

Affected packages and fixed versions:
- aiohttp (PyPI): affected all versions; fixed in 3.14.2
- aiohttp (PyPI): affected all versions; fixed in 3.14.2
- aiohttp (PyPI): affected all versions; fixed in 3.14.2

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-2026-69243/ (Markdown: https://insights.sbomify.com/CVE-2026-69243/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-69243
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-69243
- OSV: https://osv.dev/vulnerability/CVE-2026-69243

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-69243/
Summaries are generated and may contain mistakes; the official description above is the record.