HTTP Header Injection Vulnerability in tiny-http by Theopaid
CVE-2026-66753

6.3MEDIUM

Key Information:

Vendor

Tiny-http

Status
Tiny-http
Vendor
CVE Published:
28 July 2026

Badges

👾 Exploit Exists🟡 Public PoC

What is CVE-2026-66753?

The tiny-http library, up to version 0.12.0, is susceptible to an HTTP header injection vulnerability. Due to inadequate validation in its header parsing and serialization processes, attackers can inject carriage return (0x0D) and line feed (0x0A) characters into HTTP header values during both request and response phases. This vulnerability can be exploited to carry out various attacks, including response splitting, cache poisoning, session fixation via Set-Cookie injection, and security header overrides, as well as request smuggling against backends that are tolerant of line feeds.

Affected Version(s)

tiny-http 0 <= 0.12.0

Exploit Proof of Concept (PoC)

PoC code is written by security researchers to demonstrate the vulnerability can be exploited. PoC code is also a key component for weaponization which could lead to ransomware.

CVE-2026-66753 - Proof of Concept

References

https://github.com/theopaid/HTTP-Header-Injection-via-Unv...
technical-descriptionexploit
https://www.vulncheck.com/advisories/tiny-http-http-respo...
third-party-advisory

CVSS V4

Score:
6.3
Severity:
MEDIUM
Confidentiality:
None
Integrity:
Low
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
Physical
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • 🟡

    Public PoC available

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

Credit

Theodosis Paidakis
.