SAML Single Sign On <= 5.4.3 - Unauthenticated Authentication Bypass via 'SAMLResponse' Parameter Signature Algorithm Confusion
SAML Single Sign On – SSO Login has a login security issue. In some setups, an attacker may be able to bypass SAML login checks.
Quick answer
SAML Single Sign On – SSO Login should be reviewed and updated if it matches the affected versions. The recommended fix is to apply the vendor-supported patched version or the mitigation steps below, then retest the public website with Fixnx.
Who is affected
Affected versions
- SAML Single Sign On – SSO Login up to and including 5.4.3
Fixed versions
- SAML Single Sign On – SSO Login 5.4.4 or later
How to fix it
Update SAML Single Sign On – SSO Login. The old version can weaken login checks in some setups.
- Back up the site and database.
- Update SAML Single Sign On – SSO Login to SAML Single Sign On – SSO Login 5.4.4 or later.
- Check SSO settings and trusted identity provider settings.
- Review recent logins and remove unknown admin users.
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Verify the fix
- Confirm the installed version is SAML Single Sign On – SSO Login 5.4.4 or later.
- Test login with normal and blocked users to confirm access rules work.
Related categories
Trusted references
FAQ
What is affected by CVE-2026-15013?
SAML Single Sign On – SSO Login versions listed as affected should be reviewed: SAML Single Sign On – SSO Login up to and including 5.4.3.
What should I fix first?
Start with internet-facing sites, admin panels, login flows, plugins, themes, modules, packages, and systems that process user-controlled input or sensitive data.
How do I confirm the fix worked?
Apply the patched version or mitigation, clear caches where relevant, retest the affected workflow, and run a new Fixnx scan to verify public website exposure signals.
How are Fixnx security risk categories chosen?
Fixnx keeps one canonical risk page and assigns only broad, relevant categories such as ecosystem, technology area, or vulnerability class.