Summary A zip bomb can be used to execute a DoS against the aiohttp server.
Impact An attacker may be able to send a compressed request that when decompressed by aiohttp could exhaust the host's memory.
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Patch: https://github.com/aio-libs/aiohttp/commit/2b920c39002cee0ec5b402581779bbaaf7c9138a
Summary
Using CookieJar.load() with untrusted input may allow arbitrary code execution.
Impact
Most applications using this function will be doing so with the user's own data, so this is unlikely to affect many applications.
Workaround
If an application does allow attacker controlled files to be loaded, a workaround on older releases would be to sanitise the files before loading.
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Patch: https://github.com/aio-libs/aiohttp/commit/dcf40f30637e8752c76781cf6703b5a236749a00
AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Versions 3.13.2 and below allow a zip bomb to be used to execute a DoS against the AIOHTTP server. An attacker may be able to send a compressed request that when decompressed by AIOHTTP could exhaust the host's memory. This issue is fixed in version 3.13.3.
Summary When assert statements are bypassed, an infinite loop can occur, resulting in a DoS attack when processing a POST body.
Impact If optimisations are enabled (-O or PYTHONOPTIMIZE=1), and the application includes a handler that uses the Request.post() method, then an attacker may be able to execute a DoS attack with a specially crafted message.
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Patch: https://github.com/aio-libs/aiohttp/commit/bc1319ec3cbff9438a758951a30907b072561259
Summary
Cookies set with the cookies parameter on requests are sent after following a cross-origin redirect.
Impact
If a developer uses the cookies parameter on a per-request basis then sensitive data might be leaked to an attacker if they manage to control a redirect.
Workaround
If unable to upgrade, using a Cookie header in the headers parameter is not vulnerable.
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Patch: https://github.com/aio-libs/aiohttp/commit/f54c40851b0d6c4bbdab97ba518a223adda32478
Summary The Python HTTP parser may allow a request smuggling attack with the presence of non-ASCII characters.
Impact If a pure Python version of aiohttp is installed (i.e. without the usual C extensions) or AIOHTTPNOEXTENSIONS is enabled, then an attacker may be able to execute a request smuggling attack to bypass certain firewalls or proxy protections.
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Patch: https://github.com/aio-libs/aiohttp/commit/32677f2adfd907420c078dda6b79225c6f4ebce0
Summary Path normalization for static files prevents path traversal, but opens up the ability for an attacker to ascertain the existence of absolute path components.
Impact If an application uses web.static() (not recommended for production deployments), it may be possible for an attacker to ascertain the existence of path components.
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Patch: https://github.com/aio-libs/aiohttp/commit/f2a86fd5ac0383000d1715afddfa704413f0711e
AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Versions 3.13.2 and below allow for an infinite loop to occur when assert statements are bypassed, resulting in a DoS attack when processing a POST body. If optimizations are enabled (-O or PYTHONOPTIMIZE=1), and the application includes a handler that uses the Request.post() method, then an attacker may be able to execute a DoS attack with a specially crafted message. This issue is fixed in version 3.13.3.
AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Versions 3.13.2 and below allow a request to be crafted in such a way that an AIOHTTP server's memory fills up uncontrollably during processing. If an application includes a handler that uses the Request.post() method, an attacker may be able to freeze the server by exhausting the memory. This issue is fixed in version 3.13.3.
Summary
The parser allows non-ASCII decimals to be present in the Range header.
Impact
There is no known impact, but there is the possibility that there's a method to exploit a request smuggling vulnerability.
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Patch: https://github.com/aio-libs/aiohttp/commit/c7b7a044f88c71cefda95ec75cdcfaa4792b3b96
AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to version 3.12.14, the Python parser is vulnerable to a request smuggling vulnerability due to not parsing trailer sections of an HTTP request. If a pure Python version of aiohttp is installed (i.e. without the usual C extensions) or AIOHTTPNOEXTENSIONS is enabled, then an attacker may be able to execute a request smuggling attack to bypass certain firewalls or proxy protections. Version 3.12.14 contains a patch for this issue.
aiohttp is an async Python library providing both an HTTP client and a web framework. These advisories primarily apply to users of the web framework.
We'd first like to thank Radically Open Security (particularly Thomas Rinsma) for conducting a security audit. We'd also like to thank the NLnet foundation for funding the audit and development work spent on fixing these issues. Also thanks to other reporters and our regular sponsors.
All of the below issues have been fixed in version 3.13.3.
(Severity: High) CVE-2025-69223 - aiohttp HTTP Parser autodecompress feature susceptible to zip bomb https://github.com/aio-libs/aiohttp/security/advisories/GHSA-6mq8-rvhq-8wgg
Summary A zip bomb can be used to execute a DoS against the aiohttp server.
Impact An attacker may be able to send a compressed request that when decompressed by aiohttp could exhaust the host's memory.
Patch: https://github.com/aio-libs/aiohttp/commit/2b920c39002cee0ec5b402581779bbaaf7c9138a
(Severity: High) CVE-2025-69228 - Denial of service through large payloads https://github.com/aio-libs/aiohttp/security/advisories/GHSA-6jhg-hg63-jvvf
Summary A request can be crafted in such a way that an aiohttp server's memory fills up uncontrollably during processing.
Impact If an application includes a handler that uses the Request.post() method, an attacker may be able to freeze the server by exhausting the memory.
Patch: https://github.com/aio-libs/aiohttp/commit/b7dbd35375aedbcd712cbae8ad513d56d11cce60
(Severity: High) CVE-2025-69227 - DoS when bypassing asserts https://github.com/aio-libs/aiohttp/security/advisories/GHSA-jj3x-wxrx-4x23
Summary When assert statements are bypassed, an infinite loop can occur, resulting in a DoS attack when processing a POST body.
Impact If optimisations are enabled (-O or PYTHONOPTIMIZE=1), and the application includes a handler that uses the Request.post() method, then an attacker may be able to execute a DoS attack with a specially crafted message.
Patch: https://github.com/aio-libs/aiohttp/commit/bc1319ec3cbff9438a758951a30907b072561259
(Severity: Medium) CVE-2025-69229 - DoS through chunked messages https://github.com/aio-libs/aiohttp/security/advisories/GHSA-g84x-mcqj-x9qq
Summary
Handling of chunked messages can result in excessive blocking CPU usage when receiving a large number of chunks.
Impact
If an application makes use of the request.read() method in an endpoint, it may be possible for an attacker to cause the server to spend a moderate amount of blocking CPU time (e.g. 1 second) while processing the request. This could potentially lead to DoS as the server would be unable to handle other requests during that time.
Patch: https://github.com/aio-libs/aiohttp/commit/dc3170b56904bdf814228fae70a5501a42a6c712 Patch: https://github.com/aio-libs/aiohttp/commit/4ed97a4e46eaf61bd0f05063245f613469700229
(Severity: Low) CVE-2025-69230 - Cookie Parser Warning Storm
https://github.com/aio-libs/aiohttp/security/advisories/GHSA-fh55-r93g-j68g
Summary Reading multiple invalid cookies can lead to a logging storm.
Impact If the cookies attribute is accessed in an application, then an attacker may be able to trigger a storm of warning-level logs using a specially crafted Cookie header.
Patch: https://github.com/aio-libs/aiohttp/commit/64629a0834f94e46d9881f4e99c41a137e1f3326
(Severity: Low) CVE-2025-69226 - Brute-force leak of internal static file path components https://github.com/aio-libs/aiohttp/security/advisories/GHSA-54jq-c3m8-4m76
Summary Path normalization for static files prevents path traversal, but opens up the ability for an attacker to ascertain the existence of absolute path components.
Impact If an application uses web.static() (not recommended for production deployments), it may be possible for an attacker to ascertain the existence of path components.
Patch: https://github.com/aio-libs/aiohttp/commit/f2a86fd5ac0383000d1715afddfa704413f0711e
(Severity: Low) CVE-2025-69224 - Unicode processing of header values could cause parsing discrepancies https://github.com/aio-libs/aiohttp/security/advisories/GHSA-69f9-5gxw-wvc2
Summary The Python HTTP parser may allow a request smuggling attack with the presence of non-ASCII characters.
Impact If a pure Python version of aiohttp is installed (i.e. without the usual C extensions) or AIOHTTPNOEXTENSIONS is enabled, then an attacker may be able to execute a request smuggling attack to bypass certain firewalls or proxy protections.
Patch: https://github.com/aio-libs/aiohttp/commit/32677f2adfd907420c078dda6b79225c6f4ebce0
(Severity: Low) CVE-2025-69225 - Unicode match groups in regexes for ASCII protocol elements https://github.com/aio-libs/aiohttp/security/advisories/GHSA-mqqc-3gqh-h2x8
Summary
The parser allows non-ASCII decimals to be present in the Range header.
Impact
There is no known impact, but there is the possibility that there's a method to exploit a request smuggling vulnerability.
Patch: https://github.com/aio-libs/aiohttp/commit/c7b7a044f88c71cefda95ec75cdcfaa4792b3b96