CVE-2025-21993

Estado: ModificadaAlta (7.1)—

In the Linux kernel, the following vulnerability has been resolved:

iscsi_ibft: Fix UBSAN shift-out-of-bounds warning in ibft_attr_show_nic()

When performing an iSCSI boot using IPv6, iscsistart still reads the /sys/firmware/ibft/ethernetX/subnet-mask entry. Since the IPv6 prefix length is 64, this causes the shift exponent to become negative, triggering a UBSAN warning. As the concept of a subnet mask does not apply to IPv6, the value is set to ~0 to suppress the warning message.

CVSS

Versión: 3.1
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
Puntuación base: 7.1

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.21%
Percentil entre todas las CVEs puntuadas: 11
Fecha de la puntuación: 5/10/2026

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.

ExplotaciónT1068 Exploitation for Privilege Escalationprivilege escalation75 %
Impacto principalT1059 Command and Scripting Interpreterexecution60 %

AV:L/PR:L sin UI permite escalada local. UBSAN por desplazamiento negativo en IPv6 puede llevar a ejecución de código con mayor privilegio.

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

Execution Prevention Threat Intelligence Program Restrict Web-Based Content Privileged Account Management Limit Software Installation Behavior Prevention on Endpoint

Tecnologías afectadas (1)

Linux — Linux Kernel

CWE

CWE-125
CWE-125

Referencias

JSON original (NVD)

Mostrar

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      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\niscsi_ibft: Fix UBSAN shift-out-of-bounds warning in ibft_attr_show_nic()\n\nWhen performing an iSCSI boot using IPv6, iscsistart still reads the\n/sys/firmware/ibft/ethernetX/subnet-mask entry. Since the IPv6 prefix\nlength is 64, this causes the shift exponent to become negative,\ntriggering a UBSAN warning. As the concept of a subnet mask does not\napply to IPv6, the value is set to ~0 to suppress the warning message."
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