CVE-2026-43971

CVE-2026-43971 · Link Header Directive Smuggling via Unescaped target/rel/Attribute Keys in cow_link:link/1

Diese Seite enthält Fakten aus öffentlichen Sicherheitsquellen. Lesen Sie vor dem Aktualisieren die Originalmeldung.

Improper Encoding or Escaping of Output vulnerability in ninenines cowlib allows Link header directive smuggling via unescaped special characters in cow_link:link/1. cow_link:do_link/1 in cowlib interpolates the target URI, rel value, and attribute keys directly into the serialized Link: header value without escaping or token-grammar validation. A > byte in target prematurely closes the URI slot, allowing an attacker to append additional link entries with attacker-chosen rel directives. A " or \ in rel escapes the quoted string and opens new parameters. Any byte — including whitespace, =, and " — in an attribute key is emitted verbatim. Because browsers act on Link: directives such as rel="preconnect", rel="preload", and rel="prerender", an attacker who can influence these fields in an application that round-trips parsed Link headers through cow_link:link/1 can force victim browsers to make out-of-band connections to attacker-controlled origins. This issue affects cowlib: from 2.9.0 before 2.20.0.

CVSS 6.3 · Mittel · EPSS 0,5% · Korrektur verfügbar

Veröffentlicht

2026-08-18T09:01:53.199Z

Aktualisiert

2026-09-16T20:24:09.279Z

Technologie-Stack: system

Prüfen Sie Ihren Server →