miniOrange's SAML2Core library ships the same openssl_verify() tri-state authentication bypass across both its WordPress and Joomla SAML SSO products — one vendor code defect, two ecosystems, exploitation already attempted against the WordPress line

miniOrange's SAML2Core library ships the same openssl_verify() tri-state authentication bypass across both its WordPress and Joomla SAML SSO products — one vendor code defect, two ecosystems, exploitation already attempted against the WordPress line

Two independent research efforts converged on the same vendor-wide defect in miniOrange's (Xecurify) bundled SAML2Core library this week, across two different CMS ecosystems.

WordPress (miniOrange SAML 2.0 Single Sign On plugin). DigitalOcean's security team caught exploitation attempts on its own infrastructure via defense-in-depth controls — an anomalous admin-session attempt from outside the trusted network, using a bypass to obtain a valid admin session cookie, then blocked because admin-panel operations sit behind a separate network restriction: "exploitation has been attempted in the wild. DigitalOcean's defense-in-depth controls detected and blocked the activity on its infrastructure, and the identified indicators were shared to help strengthen detection and protection across the ecosystem" (Patchstack, 2026-08-21). DigitalOcean's own root-cause analysis — the first published for any paid edition — found two flaws. CVE-2026-61979 (signature algorithm confusion): the plugin lets an incoming SAML response choose its own SignatureMethod; setting it to HMAC-SHA1 makes the plugin use the IdP's public RSA key, fetched from IdP metadata and by definition not secret, as the HMAC secret — "an attacker can exploit this by setting SignatureMethod to HMAC-SHA1. As a result, the plugin allows using the trusted RSA public key PEM as the HMAC secret" (Patchstack, citing DigitalOcean, 2026-08-21) — so an attacker signs a forged assertion with a key anyone can obtain, and the plugin verifies it as genuine. CVE-2026-15981 (OpenSSL tri-state confusion): "openssl_verify() is tri-state, returning 1 for a valid signature, 0 for invalid, and -1 when OpenSSL itself errors out. The plugin loosely checked these results, and in PHP -1 is truthy (valid)" (Patchstack, 2026-08-21) — a deliberately malformed signature that trips OpenSSL's error path is accepted as valid. Both let an unauthenticated attacker forge a SAML assertion and land in /wp-admin as any existing user, admins included.

The public CVE records cover only the Free edition (3.x–5.x); DigitalOcean discovered the vendor silently patched six additional paid editions (Premium, Standard, two multisite/Enterprise tiers, VIP single/multisite) with no changelog entry and no public advisory, so a paid install on an unlisted version number was reported "already patched" by every vulnerability database checked, including Patchstack's own, because its version number exceeded the Free edition's fixed version. A vulnerable 16.x release additionally shows no managed-update prompt in the WordPress dashboard at all — the upgrade to 17.0.6 requires a manual plugin upload. Opportunistic scanning against miniOrange SSO endpoints has been observed from multiple VPN/datacenter/hosting IP ranges, consistent with automated exploitation attempts against every reachable installation regardless of edition. A public proof-of-concept exists for the Free edition.

Joomla (miniOrange SAML SSO and OAuth Client extensions). The Joomla CNA published CVE-2026-77998 (CVSS 4.0 10.0) on 2026-08-25 for miniOrange SAML SSO for Joomla — mySites.guru confirms this is the same openssl_verify() tri-state bug in the same vendor's Joomla product: "PHP's openssl_verify() does not answer yes or no. It answers one of three things: 1 if the signature is valid, 0 if it is not, and -1 if OpenSSL could not complete the check at all. That third answer is the trap" (mySites.guru, 2026-08-26), letting an attacker name and impersonate any account, Super User included, with a deliberately broken signature. A separate, simpler flaw, CVE-2026-77995 (CVSS 10.0, published 2026-08-24, credited to Krzysztof Zając of CERT PL), affects the miniOrange OAuth Client extension for Joomla: the extension trusts a client-supplied cookie value to determine which account a visitor is logged in as, with no verification at all (CWE-287) — setting the cookie to name an administrator makes the visitor one. Paid Joomla SAML editions (Basic 13.2, Standard 24.2, Premium 34.2, Enterprise 44.2) were fixed 26 August, the day after the free-line CVE was published, but the Joomla CVE record for CVE-2026-77998 still only covers the free 1.0.0–11.0.1 range; the paid OAuth Client editions have no fix at all as of this writing.

The same code defect class — a tri-state OpenSSL return value treated as a PHP boolean — exists independently in what appear to be two separately-maintained codebases from the same vendor, suggesting either copy-paste reuse of a flawed internal library across product lines or two independent implementations of the same well-known PHP gotcha. Either way, any organisation running any miniOrange SAML product on any platform should treat "we already checked WordPress" or "we already checked Joomla" as insufficient — the vendor's SAML verification code needs auditing wherever it appears.

Triage: alert on SAML AuthnResponse assertions whose SignatureMethod is HMAC-based rather than the expected RSA/DSA scheme, and on authentication log entries showing a successful SSO login immediately following a malformed or error-triggering signature-verification attempt in the web server or application log — legitimate SAML traffic never needs a signature-verification error to precede a successful login.