cyberlord92 SAML Single Sign On Plugin up to 5.4.4 on WordPress mo_saml_validate_signature signature verification

Summaryinfo

A vulnerability was found in cyberlord92 SAML Single Sign On Plugin up to 5.4.4. It has been classified as critical. The impacted element is the function mo_saml_validate_signature. This manipulation causes signature verification. This vulnerability is tracked as CVE-2026-15981. The attack is possible to be carried out remotely. No exploit exists.

Detailsinfo

A vulnerability classified as critical was found in cyberlord92 SAML Single Sign On Plugin up to 5.4.4. Affected by this vulnerability is the function mo_saml_validate_signature. The manipulation with an unknown input leads to a signature verification vulnerability. The CWE definition for the vulnerability is CWE-347. The product does not verify, or incorrectly verifies, the cryptographic signature for data. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

The SAML Single Sign On – SSO Login plugin for WordPress is vulnerable to Authentication Bypass in all versions up to, and including, 5.4.4. This is due to the mo_saml_validate_signature() function performing a loose boolean check on the raw tri-state integer returned by PHP's openssl_verify(), causing an error return value of -1 to be evaluated as truthy and therefore treated as a successful signature verification. This makes it possible for unauthenticated attackers to log in as any existing WordPress user, including administrators, by submitting a crafted SAMLResponse containing an attacker-controlled NameID and a deliberately malformed signature value that triggers an OpenSSL processing error — bypassing verification entirely and resulting in wp_set_auth_cookie() being called for the targeted account.

It is possible to read the advisory at wordfence.com. This vulnerability is known as CVE-2026-15981 since 07/16/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 07/23/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Type

• WordPress Plugin

Vendor

• cyberlord92

Name

• SAML Single Sign On Plugin

Version

• 5.4.0
• 5.4.1
• 5.4.2
• 5.4.3
• 5.4.4

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

Be aware that VulDB is the high quality source for vulnerability data.

Discussion