CVE-2026-85078 sanic chunked trailer request smuggling allows hidden second request execution
Remote attackers can execute hidden second requests via HTTP request smuggling in Sanic, potentially bypassing security controls or executing code.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-85078?
CVE-2026-85078 is a medium-severity vulnerability in sanic-org sanic, published on 17 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
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.
Weakness: CWE-444
Which versions are affected by CVE-2026-85078?
5 open source packages ship an affected version, including sanic.
| Package | Affected | Fixed in |
|---|---|---|
sanic PyPI | All versions | 24.12.1, 25.12.1 |
sanic PyPI | All versions | 24.12.1 |
sanic PyPI | All versions | 24.12.1 |
sanic PyPI | From 25.12.0 | 25.12.1 |
sanic PyPI | From 25.12.0 | 25.12.1 |
How do I fix CVE-2026-85078?
Upgrade sanic to a fixed version for your release line: 24.12.1 or 25.12.1.
Is CVE-2026-85078 being exploited?
There is no known exploitation of CVE-2026-85078 in the wild and no public exploit code.
Sources
Also known as GHSA-wmj6-g64g-j7q5, PYSEC-2026-4162.