Ecosyste.ms: Advisories

Security Advisories: GSA_kwCzR0hTQS01bTk4LXFnZzktd2g4NM4AA7vP

aiohttp vulnerable to Denial of Service when trying to parse malformed POST requests

Summary

An attacker can send a specially crafted POST (multipart/form-data) request. When the aiohttp server processes it, the server will enter an infinite loop and be unable to process any further requests.

Impact

An attacker can stop the application from serving requests after sending a single request.

---

For anyone needing to patch older versions of aiohttp, the minimum diff needed to resolve the issue is (located in _read_chunk_from_length()):

diff --git a/aiohttp/multipart.py b/aiohttp/multipart.py
index 227be605c..71fc2654a 100644
--- a/aiohttp/multipart.py
+++ b/aiohttp/multipart.py
@@ -338,6 +338,8 @@ class BodyPartReader:
         assert self._length is not None, "Content-Length required for chunked read"
         chunk_size = min(size, self._length - self._read_bytes)
         chunk = await self._content.read(chunk_size)
+        if self._content.at_eof():
+            self._at_eof = True
         return chunk
 
     async def _read_chunk_from_stream(self, size: int) -> bytes:

This does however introduce some very minor issues with handling form data. So, if possible, it would be recommended to also backport the changes in:
https://github.com/aio-libs/aiohttp/commit/cebe526b9c34dc3a3da9140409db63014bc4cf19
https://github.com/aio-libs/aiohttp/commit/7eecdff163ccf029fbb1ddc9de4169d4aaeb6597
https://github.com/aio-libs/aiohttp/commit/f21c6f2ca512a026ce7f0f6c6311f62d6a638866

Permalink: https://github.com/advisories/GHSA-5m98-qgg9-wh84
JSON: https://advisories.ecosyste.ms/api/v1/advisories/GSA_kwCzR0hTQS01bTk4LXFnZzktd2g4NM4AA7vP
Source: GitHub Advisory Database
Origin: Unspecified
Severity: High
Classification: General
Published: 15 days ago
Updated: 15 days ago

CVSS Score: 7.5
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Identifiers: GHSA-5m98-qgg9-wh84, CVE-2024-30251
References:

• https://github.com/aio-libs/aiohttp/security/advisories/GHSA-5m98-qgg9-wh84
• https://nvd.nist.gov/vuln/detail/CVE-2024-30251
• https://github.com/aio-libs/aiohttp/commit/7eecdff163ccf029fbb1ddc9de4169d4aaeb6597
• https://github.com/aio-libs/aiohttp/commit/cebe526b9c34dc3a3da9140409db63014bc4cf19
• https://github.com/aio-libs/aiohttp/commit/f21c6f2ca512a026ce7f0f6c6311f62d6a638866
• http://www.openwall.com/lists/oss-security/2024/05/02/4
• https://github.com/advisories/GHSA-5m98-qgg9-wh84

Repository: https://github.com/aio-libs/aiohttp
Blast Radius: 36.2

Affected Packages