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Vulnerability · Published Sep 17, 2026 · Assigned by GitHub_M

CVE-2026-85078sanic chunked trailer request smuggling allows hidden second request execution

Medium 6.5

In plain English

A medium-severity security flaw in sanic from sanic-org. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 44% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)6.5Medium
Exploit odds (30 days)0.5%top 56.2% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official 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 packages & fixed versions

EcosystemPackageFixed inAdvisory
PyPIsanic24.12.1GHSA-wmj6-g64g-j7q5
PyPIsanic25.12.1GHSA-wmj6-g64g-j7q5
PyPIsanic24.12.1, 25.12.1PYSEC-2026-4162

Affected products (as reported)

VendorProductVersions
sanic-org sanic < 24.12.1>= 25.12.0, < 25.12.1

Weakness: CWE-444 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

References