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CVE-2026-23383

Estado: AnalizadaAlta (7.8)—

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

bpf, arm64: Force 8-byte alignment for JIT buffer to prevent atomic tearing

struct bpf_plt contains a u64 target field. Currently, the BPF JIT allocator requests an alignment of 4 bytes (sizeof(u32)) for the JIT buffer.

Because the base address of the JIT buffer can be 4-byte aligned (e.g., ending in 0x4 or 0xc), the relative padding logic in build_plt() fails to ensure that target lands on an 8-byte boundary.

Fix this by increasing the allocation alignment requirement to 8 bytes (sizeof(u64)) in bpf_jit_binary_pack_alloc(). This anchors the base of the JIT buffer to an 8-byte boundary, allowing the relative padding math in build_plt() to correctly align the target field.

Detalles técnicos trazas, registros y código del informe original
This leads to two issues:
1. UBSAN reports misaligned-access warnings when dereferencing the
   structure.
2. More critically, target is updated concurrently via WRITE_ONCE() in
   bpf_arch_text_poke() while the JIT'd code executes ldr. On arm64,
   64-bit loads/stores are only guaranteed to be single-copy atomic if
   they are 64-bit aligned. A misaligned target risks a torn read,
   causing the JIT to jump to a corrupted address.

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.

AV:L/PR:L sin UI indica escalada local. El misalignment causa saltos a direcciones corruptas (ejecución de código arbitrario) o DoS por crash del kernel en arm64.

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 PreventionThreat Intelligence ProgramRestrict Web-Based ContentPrivileged Account ManagementLimit Software InstallationFilter Network Traffic

Tecnologías afectadas (1)

Linux — Linux Kernel

CWE

Referencias

JSON original (NVD)

Mostrar
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  "id": "CVE-2026-23383",
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          "version": "3.1",
          "baseScore": 7.8,
          "attackVector": "LOCAL",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
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      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf, arm64: Force 8-byte alignment for JIT buffer to prevent atomic tearing\n\nstruct bpf_plt contains a u64 target field. Currently, the BPF JIT\nallocator requests an alignment of 4 bytes (sizeof(u32)) for the JIT\nbuffer.\n\nBecause the base address of the JIT buffer can be 4-byte aligned (e.g.,\nending in 0x4 or 0xc), the relative padding logic in build_plt() fails\nto ensure that target lands on an 8-byte boundary.\n\nThis leads to two issues:\n1. UBSAN reports misaligned-access warnings when dereferencing the\n   structure.\n2. More critically, target is updated concurrently via WRITE_ONCE() in\n   bpf_arch_text_poke() while the JIT'd code executes ldr. On arm64,\n   64-bit loads/stores are only guaranteed to be single-copy atomic if\n   they are 64-bit aligned. A misaligned target risks a torn read,\n   causing the JIT to jump to a corrupted address.\n\nFix this by increasing the allocation alignment requirement to 8 bytes\n(sizeof(u64)) in bpf_jit_binary_pack_alloc(). This anchors the base of\nthe JIT buffer to an 8-byte boundary, allowing the relative padding math\nin build_plt() to correctly align the target field."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nbpf, arm64: Forzar alineación de 8 bytes para el búfer JIT para prevenir el desgarro atómico\n\nstruct bpf_plt contiene un campo objetivo u64. Actualmente, el asignador JIT de BPF solicita una alineación de 4 bytes (sizeof(u32)) para el búfer JIT.\n\nDebido a que la dirección base del búfer JIT puede estar alineada a 4 bytes (p. ej., terminando en 0x4 o 0xc), la lógica de relleno relativo en build_plt() no logra asegurar que target caiga en un límite de 8 bytes.\n\nEsto lleva a dos problemas:\n1. UBSAN informa advertencias de acceso desalineado al desreferenciar la estructura.\n2. Más críticamente, target se actualiza concurrentemente a través de WRITE_ONCE() en bpf_arch_text_poke() mientras el código JIT'd ejecuta ldr. En arm64, las cargas/almacenamientos de 64 bits solo se garantiza que sean atómicos de copia única si están alineados a 64 bits. Un target desalineado arriesga una lectura desgarrada, haciendo que el JIT salte a una dirección corrupta.\n\nSolucione esto aumentando el requisito de alineación de asignación a 8 bytes (sizeof(u64)) en bpf_jit_binary_pack_alloc(). Esto ancla la base del búfer JIT a un límite de 8 bytes, permitiendo que las matemáticas de relleno relativo en build_plt() alineen correctamente el campo target."
    }
  ],
  "lastModified": "2026-06-17T10:21:28.433",
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