CVE-2026-77998

CVE-2026-77998 is a critical-severity vulnerability with a CVSS 4.0 base score of 10.0. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-639.

Key facts

Description

Joomla Extension - miniorange.com - Unauthenticated Authentication Bypass via SAMLResponse Parameter in miniOrange SAML SSO < 11.0.2, SAML SP Single Sign On – Login with ADFS < 6.4, SAML SP Single Sign On – SAML SSO login with Google Apps < 6.4 - 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 Joomla 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.

Frequently asked questions

What is CVE-2026-77998?
Joomla Extension - miniorange.com - Unauthenticated Authentication Bypass via SAMLResponse Parameter in miniOrange SAML SSO < 11.0.2, SAML SP Single Sign On – Login with ADFS < 6.4, SAML SP Single Sign On – SAML SSO login with Google Apps < 6.4 - 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 Joomla 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.
How severe is CVE-2026-77998?
CVE-2026-77998 has a CVSS 4.0 base score of 10.0, rated critical severity.
Is CVE-2026-77998 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (28th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-77998?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2026-77998 published?
CVE-2026-77998 was published on 2026-08-25 and last updated on 2026-09-08.

References

Other CWE-639 (Authorization Bypass Through User-Controlled Key (IDOR)) vulnerabilities

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