# CVE-2023-47627: Request smuggling in aiohttp

> Request smuggling in aiohttp HTTP parser when extensions are disabled, allowing attackers to bypass security controls.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 14 Nov 2023
- **Updated:** 3 Nov 2025
- **Also known as:** AZL-43882, AZL-44370, CLSA-2025-1756253594, DEBIAN-CVE-2023-47627, GHSA-gfw2-4jvh-wgfg, PYSEC-2023-246, UBUNTU-CVE-2023-47627, openSUSE-SU-2024:13465-1

## What is CVE-2023-47627?

CVE-2023-47627 is a medium-severity vulnerability in aio-libs aiohttp, published on 14 Nov 2023. 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. The HTTP parser in AIOHTTP has numerous problems with header parsing, which could lead to request smuggling. This parser is only used when AIOHTTP_NO_EXTENSIONS is enabled (or not using a prebuilt wheel). These bugs have been addressed in commit `d5c12ba89` which has been included in release version 3.8.6. Users are advised to upgrade. There are no known workarounds for these issues.

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

## Which versions are affected by CVE-2023-47627?

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


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `aiohttp` | PyPI | All versions | 3.8.6 |
| `aiohttp` | PyPI | All versions | 3.8.6 |
| `aiohttp` | PyPI | All versions | 3.8.6 |
| `python-aiohttp` | openSUSE:Tumbleweed | All versions | 3.9.0-1.1 |

Products: Aiohttp Aiohttp.

## How do I fix CVE-2023-47627?

Upgrade aiohttp to 3.8.6 or later.

## Is CVE-2023-47627 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-47627 exists.

## 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-2023-47627 and fix it if it is affected.

What it is: CVE-2023-47627 is a medium-severity vulnerability in aio-libs aiohttp, published on 14 Nov 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-47627 exists.

Affected packages and fixed versions:
- aiohttp (PyPI): affected all versions; fixed in 3.8.6
- aiohttp (PyPI): affected all versions; fixed in 3.8.6
- aiohttp (PyPI): affected all versions; fixed in 3.8.6

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-2023-47627/ (Markdown: https://insights.sbomify.com/CVE-2023-47627/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-47627
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-47627
- OSV: https://osv.dev/vulnerability/CVE-2023-47627

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-47627/
Summaries are generated and may contain mistakes; the official description above is the record.