CVE-2025-69229: aio-libs aiohttp · Unthrottled Resource Allocation
Affects aio-libs aiohttpSource CVE Database V5
Not known to be exploited · CVSS 6.6 Medium : upgrade to 3.13.3 when convenient.
Data as of 26 Oct 2026, 10:12 UTC
- EPSS
- 0.4% chance of exploitation in 30 days – higher than 34% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 3.13.3
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:UExploitation evidence
Disclosed: evidence found.
CVE published 5 Jan 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade aio-libs aiohttp to 3.13.3.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| aio-libsaiohttp | Affected
| Fixed in
|
PyPIaiohttppkg:pypi/aiohttpOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
European organizations should immediately upgrade all aiohttp dependencies to version 3.13.3 or later to eliminate the vulnerability. In addition to patching, organizations should implement rate limiting and request throttling on endpoints that process chunked HTTP requests to prevent resource exhaustion. Deploying Web Application Firewalls (WAFs) with rules to detect and block abnormal chunked request patterns can provide an additional layer of defense. Monitoring CPU usage and request patterns for anomalies can help detect exploitation attempts early. For critical services, consider isolating aiohttp-based components behind reverse proxies that can enforce stricter traffic controls. Developers should review application code to avoid unnecessary use of request.read() on untrusted inputs or implement application-level limits on chunk sizes and counts. Finally, ensure that incident response plans include procedures for mitigating DoS attacks targeting asynchronous Python services.
Description
CVE-2025-69229 is a medium severity vulnerability in aiohttp versions prior to 3.13.3, an asynchronous HTTP client/server framework for Python. The flaw arises from improper handling of chunked HTTP messages, causing excessive CPU blocking when processing many chunks via the request.read() method. An attacker can exploit this to induce moderate CPU consumption (around 1 second per request), potentially leading to denial-of-service (DoS) by preventing the server from handling other requests. No authentication or user interaction is required, and the vulnerability is remotely exploitable over the network. Although no known exploits are currently in the wild, affected servers remain at risk until patched. The issue is fixed in aiohttp version 3.13.