CVE-2026-81509
MEDIUM
MEDIUM
Priority: 0.02
BB Relevance:
62/100
Published: 2026-10-26
Modified: 2026-10-26
First seen: 2026-10-29
Status: active
Attack Surface
Network
Low Complexity
No Auth
Scope Change
CVSS Vector Breakdown
AV:
Network
AC:
Low
PR:
None
UI:
Required
S:
Changed
C:
Low
I:
Low
A:
None
Description
nforwardauth is a forward auth service that allows the use of a single authentication middleware for multiple sites. Versions prior to 1.5.1 accept an unvalidated `r` query parameter on the `/login` endpoint and use them as the post-authentication redirect destination. An unauthenticated attacker can create a legitimate `nforwardauth` login URL that redirects a victim to an attacker-controlled website after the victim successfully authenticates. This issue may facilitate phishing and other social-engineering attacks by abusing the trust associated with the legitimate authentication domain. This vulnerability does not provide an unauthenticated ForwardAuth bypass. Version 1.5.1 contains a patch.