6.4

CVSS Score

3.1

-

CVSS Score

Basic Information

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CVE-2026-34993

CVE-2026-34993: AIOHTTP Vulnerable to Deserialization of Untrusted Data

AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to version 3.14.0, using CookieJar.load() with untrusted input may allow arbitrary code execution. Most applications using this function will be doing so with the user's own data, so this is unlikely to affect many applications. Version 3.14.0 patches the issue. If an application does allow attacker controlled files to be loaded, a workaround on older releases would be to sanitize the files before loading.

(GitHub Advisory)

Miggo Vulnerability Database

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CVE-2026-34993

CVE-2026-34993:

6.4

CVSS Score

3.1

-

CVSS Score

Basic Information

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Technical Details

Package Name	Ecosystem	Vulnerable Versions	First Patched Version
aiohttp	pip	< 3.14.0	3.14.0

Technical Details

Vulnerability Intelligence
Miggo AI

Root Cause Analysis

The vulnerability exists in the CookieJar.load method of the aiohttp library. Prior to the patch, this method used Python's pickle.load() function to deserialize cookie data from a file. The pickle module is known to be insecure for deserializing data from untrusted sources, as it can be exploited to execute arbitrary code. An attacker who can control the input file for the CookieJar.load method could craft a malicious pickle payload, leading to remote code execution on the server running the application.

The patch mitigates this vulnerability by changing the primary serialization format from pickle to JSON, which is a data-only format and not susceptible to code execution vulnerabilities. For backward compatibility with older cookie files, the load method now attempts to parse as JSON first. If that fails, it falls back to a restricted version of the pickle unpickler (_RestrictedCookieUnpickler). This custom unpickler maintains a strict whitelist of allowed classes, ensuring that only expected, safe cookie-related objects can be deserialized, thus preventing the execution of malicious payloads.

The primary vulnerable function is aiohttp.cookiejar.CookieJar.load. During exploitation, a profiler would show this function being called, which would then invoke the insecure pickle.load in the vulnerable versions.

Vulnerable functions

CookieJar.load

aiohttp/cookiejar.py

The `CookieJar.load` function was vulnerable because it used `pickle.load()` to deserialize data from a file without any restrictions. A malicious pickle file could be crafted to execute arbitrary code on the system during deserialization. The patch mitigates this by switching to JSON and using a restricted unpickler for legacy files.

Vulnerability Intelligence
Miggo AI

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WAF Protection Rules

WAF Rule

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Reasoning

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