sanic chunked trailer request smuggling allows hidden second request execution
13Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 6.5epss 0.3%
exploitation probability
0.3%top 77% of all CVEs
observed exploitation
nono source reports it
Sanic is an opensource python web server/framework. In version 25.12.0, Sanic's core HTTP/1.1 chunked-body handling does not fully consume the trailer-part after the terminating zero chunk before reusing the keep-alive connection buffer. A remote unauthenticated client can place attacker-controlled bytes in that trailer region, causing Sanic to parse and route them as a hidden second request after the outer request. This breaks HTTP request-boundary integrity and can provide a request-smuggling primitive when Sanic is deployed behind intermediaries. This issue is fixed in version 25.12.1.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L
Affected products
sanic-org · sanicReferences
https://github.com/sanic-org/sanic/commit/47349d689d65fa1907977ac100e867894aeafb22https://github.com/sanic-org/sanic/commit/69a10d3b06babaa9e5f6d1af577364e9e53b6deahttps://github.com/sanic-org/sanic/commit/a332796506c7c588b6930b02a8886e43eb8ea8d6https://github.com/sanic-org/sanic/pull/3164https://github.com/sanic-org/sanic/pull/3165https://github.com/sanic-org/sanic/releases/tag/v24.12.1https://github.com/sanic-org/sanic/releases/tag/v25.12.1https://github.com/sanic-org/sanic/security/advisories/GHSA-wmj6-g64g-j7q5