CVE-2026-81509

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.

CVSS v3 6.1 MEDIUM

6.1^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 2.8 / Impact : 2.7

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction REQUIRED

Confidentiality Impact LOW

Integrity Impact LOW

Availability Impact NONE

Scope CHANGED

References

Link	Resource
https://github.com/nosduco/nforwardauth/commit/664f2602f9e1459558d1c4c55019f6d48bc64c43
https://github.com/nosduco/nforwardauth/pull/71
https://github.com/nosduco/nforwardauth/releases/tag/v1.5.1
https://github.com/nosduco/nforwardauth/security/advisories/GHSA-q64r-v7j5-6hfg

Configurations

No configuration.

History

26 Oct 2026, 18:18

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-10-26 18:18

Updated : 2026-10-26 20:18

NVD link : CVE-2026-81509

Mitre link : CVE-2026-81509

CVE.ORG link : CVE-2026-81509

JSON object : View

Products Affected

No product.

CWE

CWE-601

URL Redirection to Untrusted Site ('Open Redirect')

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