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SAML Single Sign On <= 5.4.3 — Unauthenticated Authentication Bypass via 'SAMLResponse' Parameter Signature Algorithm Confusion

CVE-2026-15013Published · Updated

Action summary

Affected: ≤5.4.3Update to 5.4.4 or newer

All remediation steps
Watch plugin
Severity
Critical9.8
CVSS
9.8
CVSS 3.1 · CNA (Wordfence)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
What does this vector mean?
AV:N Attack vector
Network
AC:L Attack complexity
Low
PR:N Privileges required
None
UI:N User interaction
None
S:U Scope
Unchanged
C:H Confidentiality
High
I:H Integrity
High
A:H Availability
High
Weakness
CWE-347 Improper Verification of Cryptographic Signature
Required access
No account needed
Exploit prediction (EPSS)
No score
CISA KEV
Not listed
On this page8

Am I affected?

SAML Single Sign On – SSO Login miniorange-saml-20-single-sign-on

  1. Affected≤ 5.4.3
  2. Patched in5.4.4

Update to 5.4.4 or newer.

You are affected if you run ≤ 5.4.3. Version 5.4.4 and later are not affected by this issue.

  • Check your version: in wp-admin go to Plugins → Installed Plugins and read the version under SAML Single Sign On – SSO Login.
  • No admin access? Run a passive check of your site. It reads public files only.
  • No account is needed to exploit this. Treat any exposed site on an affected version as at risk.

What to do

  1. Update to version 5.4.4, or a newer patched version
  2. Rotate administrator passwords and application secrets if the site ran a vulnerable version while publicly reachable.
  3. Watch SAML Single Sign On – SSO Login to get an email when the next vulnerability is published.

Advisory

Source description from Wordfence Intelligence, credited to lhking.

The SAML Single Sign On – SSO Login plugin for WordPress is vulnerable to Authentication Bypass via SAML Signature Algorithm Confusion in all versions up to, and including, 5.4.3. The vulnerability exists because `Mo_SAML_Utilities::mo_saml_cast_key()` reads the `SignatureMethod` Algorithm attribute directly from the attacker-controlled `SAMLResponse` parameter rather than enforcing the locally configured algorithm, causing the plugin to recast the IdP's RSA public key as an HMAC-SHA1 shared secret and validate the forged signature against it. This makes it possible for unauthenticated attackers to forge a SAML assertion targeting any WordPress account — including administrators — obtain valid WordPress authentication cookies, and achieve full administrator-level account takeover.

Exploits & references

Proof-of-concept & detection

No public proof-of-concept or detection template is known for this vulnerability.

Advisories & patches

More in SAML Single Sign On – SSO Login

All 13
More vulnerabilities in SAML Single Sign On – SSO Login
SeverityVulnerabilityCVEPublished
High7.5Unauthenticated Denial of Service
≤6.1.0Update to 6.2.0
CVE-2026-62126
High7.3Unauthenticated Privilege Escalation
≤5.4.7Update to 6.0.0
CVE-2026-82842
High7.5Unauthenticated Authentication Bypass via X.509 Certificate Poisoning
≤5.4.6Update to 5.4.7
CVE-2026-75807
High7.3Unauthenticated Privilege Escalation
4.8.85 – 5.4.6Update to 5.4.7
CVE-2026-19842
Critical9.8Unauthenticated Privilege Escalation
≤5.4.3Update to 5.4.4
CVE-2026-61979

Timeline

  1. CVE published

    Severity critical, CVSS 9.8

  2. Record last updated

Sources & licenses

Wordfence record
Vulnerability data
Wordfence Intelligence. [object Object] Licensed under the CC BY-SA 4.0.
CVE® identifiers
[object Object]. Used under the CVE Program. CVE® is a registered trademark of The MITRE Corporation.
CVSS / CWE
National Vulnerability Database (NVD), shown unmodified. This product uses the NVD API but is not endorsed or certified by the NVD.
VulnCrest content
Summary, remediation guidance and page layout © VulnCrest. Not sourced from NVD.

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