high CVSS 7.5 EPSS 0.51%

CVE-2025-69223·Python vulnerability

AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Versions 3.13.2 and below allow a zip bomb to be used to execute a DoS against the AIOHTTP server. An attacker may be able to send a compressed request that when decompressed by AIOHTTP could exhaust the host's memory. This issue is fixed in version 3.13.3.

Severity
high
Software
Python
Fixed in
3.13.3
Published

How likely is exploitation

FIRST's Exploit Prediction Scoring System puts the probability of this CVE being exploited in the next 30 days at 0.51% — higher than 41% of all published CVEs. EPSS is an independent forecast of exploitation, not a severity rating: it says nothing about how much damage a successful attack does, which is what a CVSS score measures.

Read the two together. CVE-2025-69223 scores 7.5 on CVSS, so a successful attack would be serious — but at 0.51%, almost nobody is currently attempting it. That is a different situation from a flaw under mass exploitation, and it is usually the difference between patching on your next maintenance window and patching tonight.

Affected versions

Until: 3.13.3

Fixed in: 3.13.3

How to fix this CVE

Update AIOHTTP to version 3.13.3 or later to patch a denial-of-service vulnerability that allows attackers to exhaust server memory through malicious compressed requests. Organizations running Python applications with AIOHTTP should prioritize this update to prevent resource exhaustion attacks. Verify the patched version is installed across all production and development environments.

sudo dnf update python3-aiohttp

Defensia detects this vulnerability

What an exploitation attempt looks like

Sample log line indicative of exploitation attempts:

POST|PUT|PATCH requests with Content-Encoding: (gzip|deflate|compress|br) header where decompressed payload size exceeds 100MB or where decompression time exceeds normal thresholds; memory usage spike of >1GB within seconds of receiving such 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 request size limits and decompression bombs protection: set maximum decompressed body size to 50MB, add request rate limiting per IP (e.g., 10 requests/min), and validate Content-Encoding header against whitelist. Monitor for requests with suspiciously high compression ratios (>100:1).

How to check if you are affected

  1. Check installed AIOHTTP version: python3 -m pip show aiohttp | grep Version
  2. Verify if AIOHTTP is actively used in your applications: grep -r 'import aiohttp' /path/to/app --include='*.py'
  3. Monitor application logs for sudden memory spikes or out-of-memory errors coinciding with POST/PUT requests with Content-Encoding: gzip or deflate headers
  4. Confirm the fix: python3 -c 'import aiohttp; print(aiohttp.__version__)' and verify version is 3.13.3 or higher

FAQ

What is CVE-2025-69223?

This vulnerability in AIOHTTP allows attackers to trigger a denial-of-service condition by sending specially crafted compressed HTTP requests that decompress to massive sizes, consuming server memory until the application crashes or becomes unresponsive.

Is CVE-2025-69223 being actively exploited?

No, this vulnerability is not currently listed in CISA's Known Exploited Vulnerabilities catalog and no public exploits are available, though the attack vector is straightforward and organizations should still prioritize remediation.

What versions of Python are affected by CVE-2025-69223?

All versions of AIOHTTP up to and including 3.13.2 are vulnerable. The issue is resolved in AIOHTTP 3.13.3 and later; Python version itself is not the limiting factor but rather the AIOHTTP library version.

How do I check if my server is vulnerable to CVE-2025-69223?

Run 'python3 -m pip show aiohttp' and check if the version is 3.13.2 or below. If AIOHTTP is not installed, run 'pip list | grep aiohttp' to confirm absence or version mismatch.

Does Defensia detect CVE-2025-69223?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If AIOHTTP is installed on a monitored server, CVE-2025-69223 will appear in your dashboard with remediation steps.

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References

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