CVE-2026-34993 AIOHTTP Vulnerable to Deserialization of Untrusted Data
Attackers can achieve arbitrary code execution if an application uses CookieJar.load() with untrusted input in aiohttp.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-34993?
CVE-2026-34993 is a medium-severity unsafe deserialization vulnerability in aio-libs aiohttp, published on 2 Jun 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official description
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.
Weakness: CWE-502
Which versions are affected by CVE-2026-34993?
3 open source packages ship an affected version, including aiohttp. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
aiohttp PyPI | All versions | 3.14.0 |
aiohttp PyPI | All versions | 3.14.0 |
aiohttp PyPI | All versions | 3.14.0 |
Linux distribution packages (1)
python-aiohttp openSUSE:Tumbleweed | All versions | 3.14.0-1.1 |
Products include Aiohttp Aiohttp.
How do I fix CVE-2026-34993?
Upgrade aiohttp to 3.14.0 or later.
Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.
Is CVE-2026-34993 being exploited?
There is no known exploitation of CVE-2026-34993 in the wild and no public exploit code.
Other vulnerabilities in aio-libs aiohttp
- CVE-2024-52303 aiohttp memory leak when middleware is enabled when requesting a resource with a non-allowed method
- CVE-2025-69223 AIOHTTP's HTTP Parser auto_decompress feature is vulnerable to zip bomb
- CVE-2024-30251 Denial of service when trying to parse malformed POST requests in aiohttp
- CVE-2023-49081 aiohttp's ClientSession is vulnerable to CRLF injection via version
- CVE-2026-22815 AIOHTTP: Uncapped memory usage possible through aiohttp allowing unlimited trailer headers
Sources
Also known as AZL-89330, CLEANSTART-2026-HL56908, CLSA-2026-1789542238, CLSA-2026-1789638581, DEBIAN-CVE-2026-34993, ECHO-1919-21b7-3a3e and 21 more.