AIOHTTP vulnerable to DoS when bypassing asserts

SummaryWhen assert statements are bypassed, an infinite loop can occur, resulting in a DoS attack when processing a POST body. ImpactIf 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 execu...

PYSEC-2026-1109 AIOHTTP has unicode match groups in regexes for ASCII protocol elements

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:...

AIOHTTP has unicode match groups in regexes for ASCII protocol elements

SummaryThe parser allows non-ASCII decimals to be present in the Range header. ImpactThere is no known impact, but there is the possibility that there's a method to exploit a request smuggling vulnerability.----Patch:...

AIOHTTP's unicode processing of header values could cause parsing discrepancies

SummaryThe Python HTTP parser may allow a request smuggling attack with the presence of non-ASCII characters. ImpactIf 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...

PYSEC-2026-1097 AIOHTTP vulnerable to brute-force leak of internal static file path components

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 ascertai...

AIOHTTP vulnerable to brute-force leak of internal static file path components

SummaryPath normalization for static files prevents path traversal, but opens up the ability for an attacker to ascertain theexistence of absolute path components. ImpactIf an application uses web.static not recommended for production deployments, it may be possible for an attacker to ascertain t...

PYSEC-2026-1099 AIOHTTP's unicode processing of header values could cause parsing discrepancies

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...

AIOHTTP's HTTP Parser auto_decompress feature is vulnerable to zip bomb

SummaryA zip bomb can be used to execute a DoS against the aiohttp server. ImpactAn 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...

PYSEC-2026-1101 AIOHTTP's HTTP Parser auto_decompress feature is vulnerable to zip bomb

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/2b920c39002cee0ec5b402581779bbaaf7c91...

AIOHTTP is vulnerable to HTTP Request/Response Smuggling through incorrect parsing of chunked trailer sections

SummaryThe Python parser is vulnerable to a request smuggling vulnerability due to not parsing trailer sections of an HTTP request. ImpactIf 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...

PYSEC-2026-1452 Home Assistant does not correctly validate SSL for outgoing requests in core and used libs

Summary Problem: Potential man-in-the-middle attacks due to missing SSL certificate verification in the project codebase and used third-party libraries. Details In the past, aiohttp-session/request had the parameter verifyssl to control SSL certificate verification. This was a boolean value. In...

Home Assistant does not correctly validate SSL for outgoing requests in core and used libs

SummaryProblem: Potential man-in-the-middle attacks due to missing SSL certificate verification in the project codebase and used third-party libraries. DetailsIn the past, aiohttp-session/request had the parameter verifyssl to control SSL certificate verification. This was a boolean value. In...

aiohttp has a memory leak when middleware is enabled when requesting a resource with a non-allowed method

SummaryA memory leak can occur when a request produces a MatchInfoError. This was caused by adding an entry to a cache on each request, due to the building of each MatchInfoError producing a unique cache entry. ImpactIf the user is making use of any middlewares with aiohttp.web then it is advisab...

aiohttp allows request smuggling due to incorrect parsing of chunk extensions

SummaryThe Python parser parses newlines in chunk extensions incorrectly which can lead to request smuggling vulnerabilities under certain conditions. ImpactIf a pure Python version of aiohttp is installed i.e. without the usual C extensions or AIOHTTPNOEXTENSIONS is enabled, then an attacker may...

PYSEC-2026-1096 aiohttp has a memory leak when middleware is enabled when requesting a resource with a non-allowed method

Summary A memory leak can occur when a request produces a MatchInfoError. This was caused by adding an entry to a cache on each request, due to the building of each MatchInfoError producing a unique cache entry. Impact If the user is making use of any middlewares with aiohttp.web then it is...

PYSEC-2026-1103 aiohttp allows request smuggling due to incorrect parsing of chunk extensions

Summary The Python parser parses newlines in chunk extensions incorrectly which can lead to request smuggling vulnerabilities under certain conditions. Impact If a pure Python version of aiohttp is installed i.e. without the usual C extensions or AIOHTTPNOEXTENSIONS is enabled, then an attacker m...

PYSEC-2026-1108 In aiohttp, compressed files as symlinks are not protected from path traversal

Summary Static routes which contain files with compressed variants .gz or .br extension were vulnerable to path traversal outside the root directory if those variants are symbolic links. Details The server protects static routes from path traversal outside the root directory when...

In aiohttp, compressed files as symlinks are not protected from path traversal

SummaryStatic routes which contain files with compressed variants .gz or .br extension were vulnerable to path traversal outside the root directory if those variants are symbolic links. DetailsThe server protects static routes from path traversal outside the root directory when followsymlinks=Fal...

aiohttp vulnerable to Denial of Service when trying to parse malformed POST requests

SummaryAn attacker can send a specially crafted POST multipart/form-data request. When the aiohttp server processes it, the server will enter an infinite loop and be unable to process any further requests. ImpactAn attacker can stop the application from serving requests after sending a single...

PYSEC-2026-1098 aiohttp vulnerable to Denial of Service when trying to parse malformed POST requests

Summary An attacker can send a specially crafted POST multipart/form-data request. When the aiohttp server processes it, the server will enter an infinite loop and be unable to process any further requests. Impact An attacker can stop the application from serving requests after sending a single...