What’s Vulnerable › Vulnerabilities

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

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-17 · updated 2026-09-30
• Weakness: CWE-444

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

• sanic-org sanic: before 24.12.1; from 25.12.0, < 25.12.1

References

• https://github.com/sanic-org/sanic/commit/47349d689d65fa1907977ac100e867894aeafb22
• https://github.com/sanic-org/sanic/commit/69a10d3b06babaa9e5f6d1af577364e9e53b6dea
• https://github.com/sanic-org/sanic/commit/a332796506c7c588b6930b02a8886e43eb8ea8d6
• https://github.com/sanic-org/sanic/pull/3164
• https://github.com/sanic-org/sanic/pull/3165
• https://github.com/sanic-org/sanic/releases/tag/v24.12.1
• https://github.com/sanic-org/sanic/releases/tag/v25.12.1
• https://github.com/sanic-org/sanic/security/advisories/GHSA-wmj6-g64g-j7q5

Get alerted when CVE-2026-85078 or the next vulnerability affects your stack