CVE-2026-90961
The LdapAuth and LinOTPAuth authentication plugins in MISP contain an authentication bypass vulnerability. Both LdapAuthenticate and LinOTPAuthenticate replace CakePHP's FormAuthenticate class but fail to replicate its _checkFields() input validation guard. As a result, the email and password fields extracted from the login request are passed to downstream authentication logic without verifying that they are non-empty strings.
In the LDAP authenticator, an empty or null password is forwarded to ldap_bind().
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Per RFC 4513 section 5.1.2, a bind request with a valid DN and an empty password constitutes an unauthenticated bind, which many LDAP directory servers accept as successful. An attacker who knows any valid user email address in the directory can therefore authenticate as that user without possessing a password. Additionally, non-string values (null, false, arrays) are either coerced to empty strings by ldap_bind(), raise TypeErrors, or are misinterpreted as find conditions in _findUser(), all of which can lead to unintended authentication outcomes.
In the LinOTP authenticator, the same missing guard allows non-string credentials to be concatenated into the LinOTP verification request, and in the mixed-authentication branch an empty password is accepted against a stored hash of the empty string.
A secondary issue in the LDAP authenticator is that newly created user accounts (auto-provisioned on first LDAP login) were assigned an empty password. Because the save path skips validation, the empty string is hashed and stored. If the user later ceases to be found in LDAP and the mixed-authentication fallback is used, the stored hash of the empty string verifies against an empty password, again permitting unauthenticated access.
The vulnerability requires that the affected plugin (LdapAuth or LinOTPAuth) is enabled on the MISP instance and that the attacker knows at least one valid email address registered in the directory or MISP user store. No prior authentication is required. Successful exploitation grants the attacker the full privileges of the impersonated user, which may include administrative access to threat intelligence data.
Version affected: ≤2.5.45
CVSS
- Versión: 4.0
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
- Puntuación base: 9.3
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.64%
- Percentil entre todas las CVEs puntuadas: 49
- Fecha de la puntuación: 6/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
🎯 Técnicas ATT&CK
Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.
- Explotación
T1190Exploit Public-Facing Applicationinitial access95 % - Impacto principal
T1078Valid Accountsstealth · persistence · privilege escalation · initial access95 % - Impacto secundario
T1556Modify Authentication Processdefense impairment · persistence · credential access75 %
Vulnerabilidad de bypass de autenticación en MISP accesible sin privilegios por red (AV:N, PR:N). Permite suplantar cualquier usuario conociendo su email, otorgando acceso no autorizado y potencial acceso administrativo.
Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.
🛡️ Mitigaciones ATT&CK que cubren estas técnicas
Tecnologías afectadas (2)
⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.
CWE
- CWE-20, CWE-287
Referencias
JSON original (NVD)
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"published": "2026-09-14T14:17:21.270",
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"value": "The LdapAuth and LinOTPAuth authentication plugins in MISP contain an authentication bypass vulnerability. Both LdapAuthenticate and LinOTPAuthenticate replace CakePHP's FormAuthenticate class but fail to replicate its _checkFields() input validation guard. As a result, the email and password fields extracted from the login request are passed to downstream authentication logic without verifying that they are non-empty strings.\n\nIn the LDAP authenticator, an empty or null password is forwarded to ldap_bind(). Per RFC 4513 section 5.1.2, a bind request with a valid DN and an empty password constitutes an unauthenticated bind, which many LDAP directory servers accept as successful. An attacker who knows any valid user email address in the directory can therefore authenticate as that user without possessing a password. Additionally, non-string values (null, false, arrays) are either coerced to empty strings by ldap_bind(), raise TypeErrors, or are misinterpreted as find conditions in _findUser(), all of which can lead to unintended authentication outcomes.\n\nIn the LinOTP authenticator, the same missing guard allows non-string credentials to be concatenated into the LinOTP verification request, and in the mixed-authentication branch an empty password is accepted against a stored hash of the empty string.\n\nA secondary issue in the LDAP authenticator is that newly created user accounts (auto-provisioned on first LDAP login) were assigned an empty password. Because the save path skips validation, the empty string is hashed and stored. If the user later ceases to be found in LDAP and the mixed-authentication fallback is used, the stored hash of the empty string verifies against an empty password, again permitting unauthenticated access.\n\nThe vulnerability requires that the affected plugin (LdapAuth or LinOTPAuth) is enabled on the MISP instance and that the attacker knows at least one valid email address registered in the directory or MISP user store. No prior authentication is required. Successful exploitation grants the attacker the full privileges of the impersonated user, which may include administrative access to threat intelligence data.\n\n\nVersion affected: ≤2.5.45"
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"lastModified": "2026-09-16T13:42:47.997",
"sourceIdentifier": "5a6e4751-2f3f-4070-9419-94fb35b644e8"
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