high CVSS 7.5

CVE-2024-52303·Python vulnerability

aiohttp is an asynchronous HTTP client/server framework for asyncio and Python. In versions starting with 3.10.6 and prior to 3.10.11, a memory leak can occur when a request produces a MatchInfoError. This was caused by adding an entry to a cache on each request, due to the building of each MatchInfoError producing a unique cache entry. An attacker may be able to exhaust the memory resources of a server by sending a substantial number (100,000s to millions) of such requests. Those who use any middlewares with aiohttp.web should upgrade to version 3.10.11 to receive a patch.

Severity
high
Software
Python
Fixed in
3.10.11
Published
2024-11-18

Affected versions

From: 3.10.6

Until: 3.10.11

Fixed in: 3.10.11

How to fix this CVE

Upgrade aiohttp to version 3.10.11 or later to patch a memory leak vulnerability in the MatchInfoError handling mechanism. The vulnerability affects applications using aiohttp.web middlewares and can be exploited by sending malicious requests that trigger routing errors, causing unbounded memory consumption. Verify the update is applied and restart affected services to ensure the fix is active.

sudo dnf update python3-aiohttp

Defensia detects this vulnerability

What an exploitation attempt looks like

Sample log line indicative of exploitation attempts:

POST|GET|PUT|DELETE /[^\s]+ HTTP/1\.[01] - repeated requests from same or distributed IPs resulting in 404 or routing errors; correlated with sharp memory usage increase in aiohttp process (RSS growing 10-100MB per 1000 requests)

WAF mitigation (if patching is not yet possible)

Add this rule to your WAF to block exploitation attempts while you schedule the patch. 

Implement rate limiting to restrict requests that trigger 404/routing errors from a single IP; block requests with malformed paths designed to consistently trigger MatchInfoError; apply request throttling based on HTTP response code 404 frequency

How to check if you are affected

  1. Check installed aiohttp version: python3 -c "import aiohttp; print(aiohttp.__version__)"
  2. Verify if aiohttp.web is imported in your application: grep -r "from aiohttp import web" /path/to/app or grep -r "import aiohttp.web" /path/to/app
  3. Monitor memory usage trends during application runtime: watch -n 1 'ps aux | grep python3' or use 'top' to observe RSS memory growth over time
  4. Confirm the patch is applied by re-running: python3 -c "import aiohttp; print(aiohttp.__version__)" and verifying version is >= 3.10.11

FAQ

What is CVE-2024-52303?

CVE-2024-52303 is a memory leak vulnerability in aiohttp's routing error handler that allows attackers to exhaust server memory by sending requests that generate MatchInfoError exceptions, with each error creating a permanent cache entry that is never cleared.

Is CVE-2024-52303 being actively exploited?

No, this vulnerability is not listed in CISA's Known Exploited Vulnerabilities (KEV) catalog and has no public exploit code available, but it remains a practical denial-of-service risk if exposed to untrusted network traffic.

What versions of aiohttp are affected by CVE-2024-52303?

Versions 3.10.6 through 3.10.10 are vulnerable; version 3.10.11 and later contain the fix.

How do I check if my server is vulnerable to CVE-2024-52303?

Run: python3 -c "import aiohttp; print(aiohttp.__version__)" and compare the output against 3.10.11. If the version is 3.10.6 to 3.10.10 and your application uses aiohttp.web, you are vulnerable.

Does Defensia detect CVE-2024-52303?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If aiohttp is installed on a monitored server, CVE-2024-52303 will appear in your dashboard with remediation steps.

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References

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