CVE-2025-69226: Aiohttp Path Traversal Vulnerability

CVE-2025-69226 Overview

CVE-2025-69226 is a path traversal information disclosure vulnerability in aiohttp, an asynchronous HTTP client/server framework for asyncio and Python. Versions 3.13.2 and below contain flawed path normalization logic in the static file handler. An attacker can send crafted requests to determine the existence of absolute path components on the server filesystem. The issue affects applications that use web.static() to serve static content. Maintainers resolved the flaw in version 3.13.3.

Critical Impact
Remote unauthenticated attackers can probe the server filesystem to confirm the existence of arbitrary absolute paths, aiding reconnaissance for follow-on attacks. [CWE-22]

Affected Products

aiohttp versions 3.13.2 and below
Python applications using web.static() route handlers
aiohttp deployments serving static files without a fronting reverse proxy

Discovery Timeline

2026-01-05 - CVE-2025-69226 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-69226

Vulnerability Analysis

The vulnerability resides in aiohttp's static file dispatcher, specifically in the path normalization routine within aiohttp/web_urldispatcher.py. The routine intended to block path traversal attempts against static roots did not consistently reject URLs containing absolute path components. An attacker submitting requests with crafted path segments could observe response differences that reveal whether specific absolute paths exist on the underlying filesystem.

The flaw is an information disclosure primitive rather than direct file read. It does not permit content retrieval outside the static root, but it enables filesystem enumeration through inference. Reconnaissance data of this type frequently precedes targeted exploitation of adjacent services or configuration files.

Root Cause

The root cause is improper limitation of a pathname to a restricted directory [CWE-22]. The normalization logic in web_urldispatcher.py handled absolute path components inconsistently across platforms. The aiohttp maintainers note that web.static() is not recommended for production deployments, and the vulnerability underscores this guidance.

Attack Vector

Exploitation occurs over the network without authentication or user interaction. An attacker sends HTTP GET requests to a route registered by web.static() with path segments containing absolute path indicators. By comparing response codes, timing, or error patterns, the attacker determines whether a queried path exists. Because the attack complexity requires meeting specific configuration conditions, the CVSS 4.0 base score is 6.3.

python

# Patch excerpt from aiohttp/web_urldispatcher.py
# Reject static URLs that traverse outside static root (#11888) (#11906)
 import inspect
 import keyword
 import os
+import platform
 import re
 import sys
 import warnings

Source: aiohttp commit f2a86fd5

The full patch introduces platform-aware normalization to consistently reject URLs that resolve outside the configured static root directory.

Detection Methods for CVE-2025-69226

Indicators of Compromise

HTTP requests to web.static() routes containing absolute path prefixes such as /etc/, /root/, or Windows drive letters embedded in URL path segments
Repeated requests probing sequential filesystem paths from a single client
Anomalous 404 versus 403 response patterns from static file routes indicating enumeration attempts

Detection Strategies

Inventory Python environments and identify applications importing aiohttp with versions at or below 3.13.2
Deploy web application firewall rules to flag path segments containing absolute path characters against aiohttp endpoints
Correlate access logs to detect burst request patterns targeting static routes with unusual path structures

Monitoring Recommendations

Enable verbose access logging on aiohttp applications and forward logs to a centralized analytics platform
Alert on high-volume 404 responses from static file handlers originating from single source IPs
Track aiohttp package versions across development, staging, and production environments through software composition analysis

How to Mitigate CVE-2025-69226

Immediate Actions Required

Upgrade aiohttp to version 3.13.3 or later across all Python environments serving HTTP traffic
Audit application code for web.static() usage and replace with a production-grade static file server such as nginx or CDN offload
Restrict directory read permissions on the static root to minimize the value of any path existence disclosure

Patch Information

The fix is available in aiohttp 3.13.3. The security patch is committed as f2a86fd5ac0383000d1715afddfa704413f0711e and documented in GitHub Security Advisory GHSA-54jq-c3m8-4m76. Review the aiohttp commit details for the complete code change.

Workarounds

Front aiohttp applications with a reverse proxy such as nginx and serve static content directly from the proxy layer
Remove web.static() handlers from production routing tables until upgrades are applied
Apply URL filtering at the load balancer to reject requests containing absolute path indicators before they reach the aiohttp process

bash

# Upgrade aiohttp to the patched release
pip install --upgrade 'aiohttp>=3.13.3'

# Verify installed version
python -c "import aiohttp; print(aiohttp.__version__)"