Live Exposure Defense: From CVE to Confirmed Exposure in 12 Hours – See more

Back
New CVE Detected

CVE-2026-15981 – Authentication Bypass – SAML Single Sign On – SSO Login WordPress Plugin (versio…

Be the first to know when new zero-days emerge:

Subscribe to Email Alerts
Subscribe to RSS Feed

Summary

CVE-2026-15981 is a critical authentication bypass vulnerability in the SAML Single Sign On – SSO Login WordPress plugin (by cyberlord92/miniOrange), affecting all versions up to and including 5.4.4. The flaw allows unauthenticated remote attackers to log in as any existing WordPress user — including administrators — by submitting a crafted SAMLResponse that exploits a loose return-value check in the plugin’s signature verification function. The vulnerability carries a CVSS v3.1 score of 9.8 (Critical).

Technical details

  • Root cause: The mo_saml_validate_signature() function performs a loose boolean check on the tri-state integer returned by PHP’s openssl_verify(). When openssl_verify() returns -1 (indicating an error condition), the code incorrectly evaluates it as truthy — treating an OpenSSL processing error as a successful signature verification.
  • Trigger conditions: An attacker submits a crafted SAMLResponse to the plugin’s SAML assertion consumer endpoint containing an attacker-controlled NameID and a deliberately malformed signature value designed to trigger an internal OpenSSL error.
  • Attack vector: Network-based, requiring no authentication, no user interaction, and no prior account on the target system. Exploitation requires SAML SSO to be configured on the target WordPress site.
  • Impact: Because signature verification is bypassed entirely, the plugin proceeds to call wp_set_auth_cookie() for the attacker-specified account, granting an authenticated session as any targeted WordPress user — including administrators — resulting in full, unauthenticated administrator account takeover.

Affected software

  • SAML Single Sign On – SSO Login (WordPress plugin, slug: miniorange-saml-20-single-sign-on) — all versions up to and including 5.4.4

Severity

  • CVSS v3.1 Base Score: 9.8 (Critical)
  • Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
  • CWE: CWE-287 – Improper Authentication

Mitigation and recommended actions

  • Immediate action: Update the SAML Single Sign On – SSO Login plugin to version 5.4.5 or later. The WordPress.org plugin changelog for version 5.4.5 confirms: "Bugfix: Fixed unauthorised access issue in SAML SSO."
  • If immediate patching is not possible: Temporarily disable the SAML Single Sign On – SSO Login plugin until the update can be applied. Restricting network access to the WordPress SAML assertion consumer endpoint at the perimeter or WAF level can reduce exposure, but is not a substitute for patching.

IONIX Status

The IONIX research team is tracking ongoing exploitation attempts and recommends immediate patching. Potentially affected assets are outlined in this post.

References

Are you exposed?

Get a free report of your organization’s exposure to this CVE and threat

  • Mapping of all Assets with this Technology
  • Identification of potentially exposed assets to this CVE
  • Confirmation of verified exploitable assets
Get Exposure Report

How IONIX’s External Exposure Management Platform Detects and Validates
Zero-Days to Shrink MTTR

1

Map your entire attack surface (continously)

IONIX uses multi-factor discovery methods, including DNS analysis, certificate mapping, metadata inspection, and more, to automatically map every internet-facing asset across your environment. This includes cloud instances, third-party platforms, shadow IT, and even forgotten infrastructure that traditional tools miss.

2

Monitor for new CVEs

Dozens of threat intel feeds using agentic technology are continuously analyzed to detect the appearance of proof-of-concept code, exploit kits, and indicators of active targeting. IONIX goes further by applying AI to proactively evaluate whether emerging vulnerabilities are likely to be exploited, even before PoCs go public.

3

Identify Potential External Exposures

Not all CVEs matter. IONIX filters vulnerabilities by asking attacker-centric questions: Can it be reached from the internet? Does it require authentication? Is it being exploited in the wild? This dramatically reduces noise and focuses teams on threats that can actually be weaponized.

4

Create Safe, Scalable Exploit Validations

IONIX transforms real-world PoCs into safe, non-intrusive test payloads that can be run in production environments without disruption. These simulations are precisely targeted to the systems that are vulnerable, ensuring rapid validation without unnecessary load.

5

Execute Exploit Validations

By combining context about software stack, versioning, exposure status, and reachability, IONIX ensures that only the right payloads are executed against the right assets, maximizing efficiency and minimizing risk.

6

Drive Fast and Actionable Remediation

Results are routed through integrations with ticketing, SOAR, and SIEM tools. Issues are written in plain language, bundled into remediation clusters, and prioritized based on asset criticality, exploitability, and blast radius. This shortens mean time to remediation (MTTR) and empowers teams to act with confidence.

Are you exposed?

Get a free report of your organization’s exposure to this CVE and threat

  • Mapping of all Assets with this Technology
  • Identification of potentially exposed assets to this CVE
  • Confirmation of verified exploitable assets
Get Exposure Report
Close

Subscribe to Threat Center RSS

Copy/paste the link below into your preferred RSS reader or follow these instructions to subscribe to Slack alerts.

Open RSS feedSlack setup instructions

Close

Get Real-Time CVE Alerts to Your Email

Be the first to know when new zero-days emerge