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The vulnerability in AIOHTTP’s static file serving via `web.static()` involves path normalization designed to prevent directory traversal. However, this normalization inadequately obscures internal filesystem structure. During request processing, AIOHTTP resolves and sanitizes user-supplied paths for static resources. An attacker can systematically send crafted requests with incremental path components, such as repeated directory traversals (e.g., /static/../../../). The server’s response variations—like differing error messages, response times, or status codes for existing versus non-existent paths—allow inference of absolute path components on the host. This brute-force reconnaissance does not grant file read or write access but reveals internal directory layouts, aiding further attacks. The flaw is exploitable when applications use `web.static()` in development, as production use is discouraged. The patch enhances normalization to eliminate these informational leaks.
Platform: AIOHTTP
Version: unspecified
Vulnerability: path component leak
Severity: Low
date: Jan 5, 2026
Prediction: Jan 5, 2026
What Undercode Say:
Analytics:
curl probing example:
for dir in {1..100}; do curl -s http://target/static/../$dir/; done
Patch code reference:
aio-libs/aiohttp@f2a86fd
how Exploit:
Brute-force path requests
Observe response differences
Map internal directories
Protection from this CVE
Apply patch f2a86fd
Avoid web.static() production
Update AIOHTTP version
Impact:
Information disclosure
Reconnaissance facilitation
Low severity risk
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Sources:
Reported By: github.com
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