CVE-2026-31969

Estado: AnalizadaAlta (7.1)—

HTSlib is a library for reading and writing bioinformatics file formats. CRAM is a compressed format which stores DNA sequence alignment data using a variety of encodings and compression methods. When reading data encoded using the `BYTE_ARRAY_STOP` method, an out-by-one error in the `cram_byte_array_stop_decode_char()` function check for a full output buffer could result in a single attacker-controlled byte being written beyond the end of a heap allocation. Exploiting this bug causes a heap buffer overflow.

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If a user opens a file crafted to exploit this issue, it could lead to the program crashing, or overwriting of data and heap structures in ways not expected by the program. It may be possible to use this to obtain arbitrary code execution. Versions 1.23.1, 1.22.2 and 1.21.1 include fixes for this issue. There is no workaround for this issue.

CVSS

Versión: 4.0
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/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: 7.1

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.52%
Percentil entre todas las CVEs puntuadas: 42
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.

ExplotaciónT1203 Exploitation for Client Executionexecution85 %
Impacto principalT1059 Command and Scripting Interpreterexecution70 %
Impacto secundarioT1499.004 Application or System Exploitationimpact60 %

Vector CVSS con UI:P (interacción del usuario requerida) e acceso de red sin privilegios indica explotación en cliente (T1203). El buffer overflow heap puede llevar a ejecución de código (T1059) o crash (DoS, T1499.004).

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

Restrict Web-Based Content Privileged Account Management Limit Software Installation Filter Network Traffic Execution Prevention Behavior Prevention on Endpoint

Tecnologías afectadas (1)

Htslib — Htslib

CWE

CWE-122, CWE-787

Referencias

JSON original (NVD)

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      "value": "HTSlib is a library for reading and writing bioinformatics file formats. CRAM is a compressed format which stores DNA sequence alignment data using a variety of encodings and compression methods.  When reading data encoded using the `BYTE_ARRAY_STOP` method, an out-by-one error in the `cram_byte_array_stop_decode_char()` function check for a full output buffer could result in a single attacker-controlled byte being written beyond the end of a heap allocation. Exploiting this bug causes a heap buffer overflow. If a user opens a file crafted to exploit this issue, it could lead to the program crashing, or overwriting of data and heap structures in ways not expected by the program.  It may be possible to use this to obtain arbitrary code execution. Versions 1.23.1, 1.22.2 and 1.21.1 include fixes for this issue. There is no workaround for this issue."
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      "value": "HTSlib es una biblioteca para leer y escribir formatos de archivo bioinformáticos. CRAM es un formato comprimido que almacena datos de alineación de secuencias de ADN utilizando una variedad de codificaciones y métodos de compresión. Al leer datos codificados usando el método 'BYTE_ARRAY_STOP', un error de uno de más en la comprobación de la función 'cram_byte_array_stop_decode_char()' para un búfer de salida lleno podría resultar en que un solo byte controlado por el atacante se escriba más allá del final de una asignación de memoria dinámica. Explotar este error causa un desbordamiento de búfer de heap. Si un usuario abre un archivo diseñado para explotar este problema, podría llevar a que el programa falle, o a la sobrescritura de datos y estructuras de heap de maneras no esperadas por el programa. Podría ser posible usar esto para obtener ejecución de código arbitrario. Las versiones 1.23.1, 1.22.2 y 1.21.1 incluyen correcciones para este problema. No hay solución alternativa para este problema."
    }
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  "lastModified": "2026-06-17T10:34:51.773",
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