CVE-2026-23383

#include <stdio.h> #include <stdint.h> // Simulating the vulnerable structure layout struct bpf_plt { uint32_t dummy; // Simulating padding/other fields uint64_t target; // Requires 8-byte alignment }; /* * PoC Logic: * To trigger this vulnerability, an attacker needs to: * 1. Load a specific eBPF program that forces the JIT compiler * to allocate a buffer at a 4-byte aligned address (e.g., ending in 0x4). * 2. The JIT builds a PLT (Procedure Linkage Table) entry where 'target' * is misaligned. * 3. Trigger a concurrent update to 'target' via bpf_arch_text_poke() * while the JIT'd code executes an ldr instruction from that address. * 4. On ARM64, this causes a torn read (atomicity violation), * leading to a jump to a corrupted address. */ int main() { printf("PoC for CVE-2026-23383: BPF JIT Atomic Tearing\n"); printf("Requires: ARM64 Linux Kernel with vulnerable BPF JIT\n"); printf("Impact: Kernel crash or potential code execution\n"); return 0; }

{"cve": {"id": "CVE-2026-23383", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-03-25T11:16:38.487", "lastModified": "2026-04-24T18:42:21.773", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "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."}], "metrics": {"cvssMetricV31": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "NVD-CWE-noinfo"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.0.1", "versionEndExcluding": "6.12.77", "matchCriteriaId": "5D973B34-246F-4A22-882C-BBD5EB00997D"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "6.18.17", "matchCriteriaId": "A5E006E4-59C7-43C1-9231-62A72219F2BA"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "6.19.7", "matchCriteriaId": "69245D10-0B71-485E-80C3-A64F077004D3"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:6.0:-:*:*:*:*:*:*", "matchCriteriaId": "7BE551E5-89CF-47A8-9B26-03CE727FBA37"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*", "matchCriteriaId": "F253B622-8837-4245-BCE5-A7BF8FC76A16"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*", "matchCriteriaId": "4AE85AD8-4641-4E7C-A2F4-305E2CD9EE64"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*", "matchCriteriaId": "F666C8D8-6538-46D4-B318-87610DE64C34"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*", "matchCriteriaId": "02259FDA-961B-47BC-AE7F-93D7EC6E90C2"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:*", "matchCriteriaId": "58A ... 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