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CVE-2026-81509 (GCVE-0-2026-81509)

Vulnerability from nvd – Published: 2026-10-26 17:19 – Updated: 2026-10-26 19:34

Title

nforwardauth: Unvalidated r parameter allows post-authentication open redirect

Summary

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.

Severity

6.1 (Medium)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-10-26 19:29 UTC

CWE

CWE-601 - URL Redirection to Untrusted Site ('Open Redirect')

Assigner

GitHub_M CNA under the mitre root

CNA scorecard C 72/100 over 7820 records in the last 180 days details

References

4 references

URL	Tags
https://github.com/nosduco/nforwardauth/security/…	x_refsource_CONFIRM
https://github.com/nosduco/nforwardauth/pull/71	x_refsource_MISC
https://github.com/nosduco/nforwardauth/commit/66…	x_refsource_MISC
https://github.com/nosduco/nforwardauth/releases/…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
nosduco	nforwardauth	Affected: < 1.5.1

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-81509",
                "options": [
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                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-10-26T19:29:40.719883Z",
                "version": "2.0.3"
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          "shortName": "CISA-ADP"
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        "title": "CISA ADP Vulnrichment"
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          "value": "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."
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      "metrics": [
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          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 6.1,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "LOW",
            "integrityImpact": "LOW",
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          "tags": [
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          "url": "https://github.com/nosduco/nforwardauth/releases/tag/v1.5.1"
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      "source": {
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      "title": "nforwardauth: Unvalidated r parameter allows post-authentication open redirect"
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    "datePublished": "2026-10-26T17:19:15.467Z",
    "dateReserved": "2026-08-26T20:58:58.084Z",
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    "state": "PUBLISHED"
  },
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}

CVE-2026-81509 (GCVE-0-2026-81509)

Vulnerability from cvelistv5 – Published: 2026-10-26 17:19 – Updated: 2026-10-26 19:34

Title

nforwardauth: Unvalidated r parameter allows post-authentication open redirect

Summary

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.

Severity

6.1 (Medium)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-10-26 19:29 UTC

CWE

CWE-601 - URL Redirection to Untrusted Site ('Open Redirect')

Assigner

GitHub_M CNA under the mitre root

CNA scorecard C 72/100 over 7820 records in the last 180 days details

References

4 references

URL	Tags
https://github.com/nosduco/nforwardauth/security/…	x_refsource_CONFIRM
https://github.com/nosduco/nforwardauth/pull/71	x_refsource_MISC
https://github.com/nosduco/nforwardauth/commit/66…	x_refsource_MISC
https://github.com/nosduco/nforwardauth/releases/…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
nosduco	nforwardauth	Affected: < 1.5.1

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-81509",
                "options": [
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                    "Exploitation": "none"
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                    "Automatable": "no"
                  },
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                    "Technical Impact": "partial"
                  }
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                "role": "CISA Coordinator",
                "timestamp": "2026-10-26T19:29:40.719883Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
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          "dateUpdated": "2026-10-26T19:34:58.155Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "nforwardauth",
          "vendor": "nosduco",
          "versions": [
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        }
      ],
      "metrics": [
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          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
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            "confidentialityImpact": "LOW",
            "integrityImpact": "LOW",
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          "tags": [
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    "state": "PUBLISHED"
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}

Find a vulnerability

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2 vulnerabilities by nosduco

CVE-2026-81509 (GCVE-0-2026-81509)

CVE-2026-81509 (GCVE-0-2026-81509)