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Vulnerability · Published Sep 17, 2026 · Assigned by GitHub_M

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

High 8.2

In plain English

A high-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 42% of all known vulnerabilities).

Severity (CVSS 3.1)8.2High
Exploit odds (30 days)0.5%top 58.0% 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. 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.

Affected products (as reported)

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

Weakness: CWE-113 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N

References