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Medium · 6.5 CVE-2026-85078 EUVD-2026-81577GHSA-wmj6-g64g-j7q5PYSEC-2026-4162

sanic chunked trailer request smuggling allows hidden second request execution

Published Sep 17, 2026 · Updated Sep 17, 2026 · Assigned by GitHub_M

Description

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.

Affected products

VendorProductAffectedFixed
sanic-org sanic < 24.12.1, >= 25.12.0, < 25.12.1 —

Affected packages

EcosystemPackageAffectedFixedRecord
PyPI sanic < 24.12.1 24.12.1 GHSA-wmj6-g64g-j7q5
PyPI sanic >= 25.12.0, < 25.12.1 25.12.1 GHSA-wmj6-g64g-j7q5
PyPI sanic < 24.12.1 · >= 25.12.0, < 25.12.1 24.12.1, 25.12.1 PYSEC-2026-4162

References