AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.4, aiohttp decompresses each member of a payload containing many concatenated gzip, deflate, or zstd streams by passing the entire remaining input to a new decompressor, causing quadratic CPU use. Empty members produce no output, so client_max_size and output backpressure do not limit the work.
A remote attacker can block a server event loop with a crafted compressed request body or WebSocket message, and a malicious server can similarly block a client. This issue is fixed in version 3.14.4.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Attack Requirements
None
No additional conditions
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
None
No data leak
Integrity
None
No data modification
Availability
High
Complete denial of service
CVSS Vector v4.0
Weakness Type (CWE)
References 6
https://github.com/aio-libs/aiohttp/commit/d041d4d0fd48c3f0832084d33be16cf1c483…
security-advisories@github.com
https://github.com/aio-libs/aiohttp/commit/d925a80539ffd227da1d93ab4a5bff123cc7…
security-advisories@github.com
https://github.com/aio-libs/aiohttp/pull/13362
security-advisories@github.com
https://github.com/aio-libs/aiohttp/pull/13391
security-advisories@github.com
https://github.com/aio-libs/aiohttp/releases/tag/v3.14.4
security-advisories@github.com
https://github.com/aio-libs/aiohttp/security/advisories/GHSA-h4cc-hm5h-fmm9
security-advisories@github.com