Dub Open Redirect via Unrestricted redir_url Parameter

Advisories

Dub Open Redirect via Unrestricted redir_url Parameter

severity: medium
date: 9/4/2026
Affecting: dub <= 73415cf5e6be13ce9adb7ba5e97474307db34a17
CVE: CVE-2026-85676
CWE: CWE-601 URL Redirection to Untrusted Site ('Open Redirect')
CVSS: 5.3
CVSS V4 Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
References: GitHub Issue #4337
https://github.com/dubinc/dub
https://github.com/dubinc/dub/blob/73415cf5e6be13ce9adb7ba5e97474307db34a17/apps/web/lib/middleware/utils/get-final-url.ts
Credit: George Chen
Description: Dub contains an open redirect vulnerability in the redir_url query parameter that is accepted on every short link without validation or domain allowlist enforcement. Attackers can append the redir_url parameter to any short link to redirect visitors to arbitrary external URLs through the trusted Dub domain, bypassing destination blacklists and potentially enabling phishing attacks with link cloaking enabled.

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