CVE-2026-31570
Estado: AnalizadaAlta (8.8)—
In the Linux kernel, the following vulnerability has been resolved:
can: gw: fix OOB heap access in cgw_csum_crc8_rel()
cgw_csum_crc8_rel() correctly computes bounds-safe indices via calc_idx():
However, the loop and the result write then use the raw s8 fields directly instead of the computed variables:
With from_idx = to_idx = result_idx = -64 on a 64-byte CAN FD frame, calc_idx(-64, 64) = 0 so the guard passes, but the loop iterates with i = -64, reading cf->data[-64], and the write goes to cf->data[-64]. This write might end up to 56 (7.0-rc) or 40 (<= 6.19) bytes before the start of the canfd_frame on the heap.
Leer descripción completaMostrar menos
The companion function cgw_csum_xor_rel() uses `from`/`to`/`res` correctly throughout; fix cgw_csum_crc8_rel() to match.
To configure the can-gw crc8 checksums CAP_NET_ADMIN is needed.
Detalles técnicos trazas, registros y código del informe original
int from = calc_idx(crc8->from_idx, cf->len);
int to = calc_idx(crc8->to_idx, cf->len);
int res = calc_idx(crc8->result_idx, cf->len);
if (from < 0 || to < 0 || res < 0)
return;
for (i = crc8->from_idx; ...) /* BUG: raw negative index */
cf->data[crc8->result_idx] = ...; /* BUG: raw negative index */
Confirmed with KASAN on linux-7.0-rc2:
BUG: KASAN: slab-out-of-bounds in cgw_csum_crc8_rel+0x515/0x5b0
Read of size 1 at addr ffff8880076619c8 by task poc_cgw_oob/62CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Puntuación base: 8.8
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.41%
- Percentil entre todas las CVEs puntuadas: 33
- 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.
- Explotación
T1210Exploitation of Remote Serviceslateral movement75 % - Impacto principal
T1068Exploitation for Privilege Escalationprivilege escalation80 % - Impacto secundario
T1005Data from Local Systemcollection70 %
AV:A (red adyacente) sin privilegios requiere T1210. La corrupción de heap OOB permite escalada (acceso root/admin) y lectura de datos sensibles de memoria. Requiere CAP_NET_ADMIN local previo.
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
Tecnologías afectadas (1)
CWE
- CWE-125
Referencias
- https://git.kernel.org/stable/c/54ecdf76a55e75c1f5085e440f8ab671a3283ef5
- https://git.kernel.org/stable/c/66b689efd08227da2c5ca49b58b30a95d23c695a
- https://git.kernel.org/stable/c/84f8b76d24273175a22713e83e90874e1880d801
- https://git.kernel.org/stable/c/999ca48d55a8a46da21519db7e834e5867200379
- https://git.kernel.org/stable/c/a025283d7f7404c739225e457fb99db2368bb544
- https://git.kernel.org/stable/c/b9c310d72783cc2f30d103eed83920a5a29c671a
- https://git.kernel.org/stable/c/c4e8eaa75fa0b6bcbfa5356d6195c4ad0e05e57a
- https://git.kernel.org/stable/c/e7c99348b0612b2bc02d5ce6ff9873261cc7605f
JSON original (NVD)
Mostrar
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncan: gw: fix OOB heap access in cgw_csum_crc8_rel()\n\ncgw_csum_crc8_rel() correctly computes bounds-safe indices via calc_idx():\n\n int from = calc_idx(crc8->from_idx, cf->len);\n int to = calc_idx(crc8->to_idx, cf->len);\n int res = calc_idx(crc8->result_idx, cf->len);\n\n if (from < 0 || to < 0 || res < 0)\n return;\n\nHowever, the loop and the result write then use the raw s8 fields directly\ninstead of the computed variables:\n\n for (i = crc8->from_idx; ...) /* BUG: raw negative index */\n cf->data[crc8->result_idx] = ...; /* BUG: raw negative index */\n\nWith from_idx = to_idx = result_idx = -64 on a 64-byte CAN FD frame,\ncalc_idx(-64, 64) = 0 so the guard passes, but the loop iterates with\ni = -64, reading cf->data[-64], and the write goes to cf->data[-64].\nThis write might end up to 56 (7.0-rc) or 40 (<= 6.19) bytes before the\nstart of the canfd_frame on the heap.\n\nThe companion function cgw_csum_xor_rel() uses `from`/`to`/`res`\ncorrectly throughout; fix cgw_csum_crc8_rel() to match.\n\nConfirmed with KASAN on linux-7.0-rc2:\n BUG: KASAN: slab-out-of-bounds in cgw_csum_crc8_rel+0x515/0x5b0\n Read of size 1 at addr ffff8880076619c8 by task poc_cgw_oob/62\n\nTo configure the can-gw crc8 checksums CAP_NET_ADMIN is needed."
}
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