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CVE-2024-53861

Estado: AnalizadaAlta (7.5)—

pyjwt is a JSON Web Token implementation in Python. An incorrect string comparison is run for `iss` checking, resulting in `"acb"` being accepted for `"_abc_"`. This is a bug introduced in version 2.10.0: checking the "iss" claim changed from `isinstance(issuer, list)` to `isinstance(issuer, Sequence)`. Since str is a Sequnce, but not a list, `in` is also used for string comparison. This results in `if "abc" not in "__abcd__":` being checked instead of `if "abc" != "__abc__":`. Signature checks are still present so real world impact is likely limited to denial of service scenarios. This issue has been patched in version 2.10.1. All users are advised to upgrade. There are no known workarounds for this vulnerability.

CVSS

Probabilidad de explotación (EPSS)

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.

Vulnerabilidad remota sin autenticación (AV:N, PR:N, UI:N) en librería pública; comparación de cadenas incorrecta permite bypass de validación de claims JWT. Impacto DoS por rechazo de tokens legítimos o procesamiento anómalo.

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

Filter Network TrafficVulnerability ScanningPrivileged Account ManagementNetwork SegmentationLimit Access to Resource Over NetworkApplication Isolation and Sandboxing

Tecnologías afectadas (1)

Pyjwt Project — Pyjwt

CWE

Referencias

JSON original (NVD)

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      "value": "pyjwt is a JSON Web Token implementation in Python. An incorrect string comparison is run for `iss` checking, resulting in `\"acb\"` being accepted for `\"_abc_\"`. This is a bug introduced in version 2.10.0: checking the \"iss\" claim changed from `isinstance(issuer, list)` to `isinstance(issuer, Sequence)`. Since str is a Sequnce, but not a list, `in` is also used for string comparison. This results in `if \"abc\" not in \"__abcd__\":` being checked instead of `if \"abc\" != \"__abc__\":`. Signature checks are still present so real world impact is likely limited to denial of service scenarios. This issue has been patched in version 2.10.1. All users are advised to upgrade. There are no known workarounds for this vulnerability."
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      "value": "pyjwt es una implementación de JSON Web Token en Python. Se ejecuta una comparación de cadena incorrecta para la comprobación de `iss`, lo que da como resultado que `\"acb\"` se acepte en lugar de `\"_abc_\"`. Este es un error introducido en la versión 2.10.0: la comprobación de la reclamación \"iss\" cambió de `isinstance(issuer, list)` a `isinstance(issuer, Sequence)`. Dado que str es una secuencia, pero no una lista, `in` también se utiliza para la comparación de cadenas. Esto da como resultado que se compruebe `if \"abc\" not in \"__abcd__\":` en lugar de `if \"abc\" != \"__abc__\":`. Las comprobaciones de firma aún están presentes, por lo que es probable que el impacto en el mundo real se limite a escenarios de denegación de servicio. Este problema se ha corregido en la versión 2.10.1. Se recomienda a todos los usuarios que actualicen. No existen workarounds conocidos para esta vulnerabilidad."
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