CVE-2024-49861

Estado: ModificadaAlta (7.1)—

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

bpf: Fix helper writes to read-only maps

Lonial found an issue that despite user- and BPF-side frozen BPF map (like in case of .rodata), it was still possible to write into it from a BPF program side through specific helpers having ARG_PTR_TO_{LONG,INT} as arguments.

In check_func_arg() when the argument is as mentioned, the meta->raw_mode is never set. Later, check_helper_mem_access(), under the case of PTR_TO_MAP_VALUE as register base type, it assumes BPF_READ for the subsequent call to check_map_access_type() and given the BPF map is read-only it succeeds.

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The helpers really need to be annotated as ARG_PTR_TO_{LONG,INT} | MEM_UNINIT when results are written into them as opposed to read out of them. The latter indicates that it's okay to pass a pointer to uninitialized memory as the memory is written to anyway.

However, ARG_PTR_TO_{LONG,INT} is a special case of ARG_PTR_TO_FIXED_SIZE_MEM just with additional alignment requirement. So it is better to just get rid of the ARG_PTR_TO_{LONG,INT} special cases altogether and reuse the fixed size memory types. For this, add MEM_ALIGNED to additionally ensure alignment given these helpers write directly into the args via *<ptr> = val. The .arg*_size has been initialized reflecting the actual sizeof(*<ptr>).

MEM_ALIGNED can only be used in combination with MEM_FIXED_SIZE annotated argument types, since in !MEM_FIXED_SIZE cases the verifier does not know the buffer size a priori and therefore cannot blindly write *<ptr> = val.

CVSS

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

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.24%
Percentil entre todas las CVEs puntuadas: 14
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.

ExplotaciónT1068 Exploitation for Privilege Escalationprivilege escalation85 %
Impacto principalT1565.001 Stored Data Manipulationimpact75 %
Impacto secundarioT1499.004 Application or System Exploitationimpact60 %

Escalada de privilegios local (AV:L PR:L) permitiendo escritura en mapas BPF protegidos (I:H), violando controles de lectura. El atacante con permisos locales bypassa restricciones de memoria mediante helpers de BPF.

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

Threat Intelligence Program Restrict File and Directory Permissions Remote Data Storage Filter Network Traffic Execution Prevention Encrypt Sensitive Information

Tecnologías afectadas (1)

Linux — Linux Kernel

CWE

NVD-CWE-noinfo

Referencias

JSON original (NVD)

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      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix helper writes to read-only maps\n\nLonial found an issue that despite user- and BPF-side frozen BPF map\n(like in case of .rodata), it was still possible to write into it from\na BPF program side through specific helpers having ARG_PTR_TO_{LONG,INT}\nas arguments.\n\nIn check_func_arg() when the argument is as mentioned, the meta->raw_mode\nis never set. Later, check_helper_mem_access(), under the case of\nPTR_TO_MAP_VALUE as register base type, it assumes BPF_READ for the\nsubsequent call to check_map_access_type() and given the BPF map is\nread-only it succeeds.\n\nThe helpers really need to be annotated as ARG_PTR_TO_{LONG,INT} | MEM_UNINIT\nwhen results are written into them as opposed to read out of them. The\nlatter indicates that it's okay to pass a pointer to uninitialized memory\nas the memory is written to anyway.\n\nHowever, ARG_PTR_TO_{LONG,INT} is a special case of ARG_PTR_TO_FIXED_SIZE_MEM\njust with additional alignment requirement. So it is better to just get\nrid of the ARG_PTR_TO_{LONG,INT} special cases altogether and reuse the\nfixed size memory types. For this, add MEM_ALIGNED to additionally ensure\nalignment given these helpers write directly into the args via *<ptr> = val.\nThe .arg*_size has been initialized reflecting the actual sizeof(*<ptr>).\n\nMEM_ALIGNED can only be used in combination with MEM_FIXED_SIZE annotated\nargument types, since in !MEM_FIXED_SIZE cases the verifier does not know\nthe buffer size a priori and therefore cannot blindly write *<ptr> = val."
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      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: bpf: Arregla las escrituras del ayudante en mapas de solo lectura Lonial encontró un problema que a pesar del mapa BPF congelado del lado del usuario y del BPF (como en el caso de .rodata), aún era posible escribir en él desde el lado del programa BPF a través de ayudantes específicos que tienen ARG_PTR_TO_{LONG,INT} como argumentos. En check_func_arg() cuando el argumento es como se menciona, el meta-&gt;raw_mode nunca se establece. Más tarde, check_helper_mem_access(), bajo el caso de PTR_TO_MAP_VALUE como tipo base de registro, asume BPF_READ para la llamada posterior a check_map_access_type() y dado que el mapa BPF es de solo lectura, tiene éxito. Los ayudantes realmente necesitan ser anotados como ARG_PTR_TO_{LONG,INT} | MEM_UNINIT cuando los resultados se escriben en ellos en lugar de leerse de ellos. Este último indica que está bien pasar un puntero a la memoria no inicializada, ya que la memoria se escribe de todos modos. Sin embargo, ARG_PTR_TO_{LONG,INT} es un caso especial de ARG_PTR_TO_FIXED_SIZE_MEM solo que con un requisito de alineación adicional. Por lo tanto, es mejor deshacerse de los casos especiales ARG_PTR_TO_{LONG,INT} por completo y reutilizar los tipos de memoria de tamaño fijo. Para esto, agregue MEM_ALIGNED para garantizar adicionalmente la alineación dado que estos ayudantes escriben directamente en los argumentos a través de * = val. El .arg*_size se ha inicializado reflejando el tamaño real de (*). MEM_ALIGNED solo se puede usar en combinación con los tipos de argumentos anotados MEM_FIXED_SIZE, ya que en los casos !MEM_FIXED_SIZE el verificador no conoce el tamaño del búfer a priori y, por lo tanto, no puede escribir ciegamente * = val."
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