CVE-2026-21621

Estado: ModificadaAlta (7)—

Incorrect Authorization vulnerability in hexpm hexpm/hexpm ('Elixir.HexpmWeb.API.OAuthController' module) allows Privilege Escalation.

An API key created with read-only permissions (domain: "api", resource: "read") can be escalated to full write access under specific conditions.

When exchanging a read-only API key via the OAuth client_credentials grant, the resource qualifier is ignored. The resulting JWT receives the broad "api" scope instead of the expected "api:read" scope. This token is therefore treated as having full API access.

If an attacker is able to obtain a victim's read-only API key and a valid 2FA (TOTP) code for the victim account, they can use the incorrectly scoped JWT to create a new full-access API key with unrestricted API permissions that does not expire by default and can perform write operations such as publishing, retiring, or modifying packages.

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This vulnerability is associated with program files lib/hexpm_web/controllers/api/oauth_controller.ex and program routines 'Elixir.HexpmWeb.API.OAuthController':validate_scopes_against_key/2.

This issue affects hexpm: from 71829cb6f6559bcceb1ef4e43a2fb8cdd3af654b before 71c127afebb7ed7cc637eb231b98feb802d62999.

CVSS

Versión: 4.0
Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:L/SC:N/SI:H/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: 7

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.34%
Percentil entre todas las CVEs puntuadas: 25
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.

ExplotaciónT1210 Exploitation of Remote Serviceslateral movement75 %
Impacto principalT1078.004 Cloud Accountsstealth · persistence · privilege escalation · initial access85 %
Impacto secundarioT1556.003 Pluggable Authentication Modulesdefense impairment · persistence · credential access80 %

Vulnerabilidad de autorización en OAuth que permite escalar permisos de lectura a escritura completa en API. Requiere credenciales previas (PR:L) y acceso a la red; impacta en creación de cuentas/tokens con permisos elevados (T1078.004, T1556.003).

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

Privileged Account Management Multi-factor Authentication Active Directory Configuration Vulnerability Scanning User Training User Account Management

Tecnologías afectadas (1)

HEX — Hexpm

CWE

CWE-863

Referencias

JSON original (NVD)

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      "value": "Incorrect Authorization vulnerability in hexpm hexpm/hexpm ('Elixir.HexpmWeb.API.OAuthController' module) allows Privilege Escalation.\n\nAn API key created with read-only permissions (domain: \"api\", resource: \"read\") can be escalated to full write access under specific conditions.\n\nWhen exchanging a read-only API key via the OAuth client_credentials grant, the resource qualifier is ignored. The resulting JWT receives the broad \"api\" scope instead of the expected \"api:read\" scope. This token is therefore treated as having full API access.\n\nIf an attacker is able to obtain a victim's read-only API key and a valid 2FA (TOTP) code for the victim account, they can use the incorrectly scoped JWT to create a new full-access API key with unrestricted API permissions that does not expire by default and can perform write operations such as publishing, retiring, or modifying packages.\n\nThis vulnerability is associated with program files lib/hexpm_web/controllers/api/oauth_controller.ex and program routines 'Elixir.HexpmWeb.API.OAuthController':validate_scopes_against_key/2.\n\nThis issue affects hexpm: from 71829cb6f6559bcceb1ef4e43a2fb8cdd3af654b before 71c127afebb7ed7cc637eb231b98feb802d62999."
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      "value": "Vulnerabilidad de autorización incorrecta en hexpm hexpm/hexpm (módulo 'Elixir.HexpmWeb.API.OAuthController') permite la escalada de privilegios.\n\nUna clave API creada con permisos de solo lectura (dominio: \"api\", recurso: \"read\") puede ser escalada a acceso completo de escritura bajo condiciones específicas.\n\nAl intercambiar una clave API de solo lectura a través de la concesión OAuth client_credentials, el calificador de recurso es ignorado. El JWT resultante recibe el ámbito amplio \"api\" en lugar del ámbito esperado \"api:read\". Este token es, por lo tanto, tratado como si tuviera acceso completo a la API.\n\nSi un atacante es capaz de obtener una clave API de solo lectura de una víctima y un código 2FA (TOTP) válido para la cuenta de la víctima, pueden usar el JWT con ámbito incorrecto para crear una nueva clave API de acceso completo con permisos de API ilimitados que no expira por defecto y puede realizar operaciones de escritura como publicar, retirar o modificar paquetes.\n\nEsta vulnerabilidad está asociada con los archivos de programa lib/hexpm_web/controllers/api/oauth_controller.ex y las rutinas de programa 'Elixir.HexpmWeb.API.OAuthController':validate_scopes_against_key/2.\n\nEste problema afecta a hexpm: desde 71829cb6f6559bcceb1ef4e43a2fb8cdd3af654b antes de 71c127afebb7ed7cc637eb231b98feb802d62999."
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  "lastModified": "2026-06-17T10:18:49.260",
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