CVE-2026-23383 (GCVE-0-2026-23383)

Vulnerability from cvelistv5 – Published: 2026-03-25 10:28 – Updated: 2026-04-02 14:44
VLAI?
Title
bpf, arm64: Force 8-byte alignment for JIT buffer to prevent atomic tearing
Summary
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. 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. 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.
Severity ?
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: b2ad54e1533e91449cb2a371e034942bd7882b58 , < 80ad264da02cc4aee718e799c2b79f0f834673dc (git)
Affected: b2ad54e1533e91449cb2a371e034942bd7882b58 , < 519b1ad91de5bf7a496f2b858e9212db6328e1de (git)
Affected: b2ad54e1533e91449cb2a371e034942bd7882b58 , < 66959ed481a474eaae278c7f6860a2a9b188a4d6 (git)
Affected: b2ad54e1533e91449cb2a371e034942bd7882b58 , < ef06fd16d48704eac868441d98d4ef083d8f3d07 (git)
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    Linux Linux Affected: 6.0
Unaffected: 0 , < 6.0 (semver)
Unaffected: 6.12.77 , ≤ 6.12.* (semver)
Unaffected: 6.18.17 , ≤ 6.18.* (semver)
Unaffected: 6.19.7 , ≤ 6.19.* (semver)
Unaffected: 7.0-rc2 , ≤ * (original_commit_for_fix)
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{
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        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "arch/arm64/net/bpf_jit_comp.c"
          ],
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          "vendor": "Linux",
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              "version": "0",
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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\u0027d 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."
        }
      ],
      "metrics": [
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            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
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        "dateUpdated": "2026-04-02T14:44:28.675Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/519b1ad91de5bf7a496f2b858e9212db6328e1de"
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          "url": "https://git.kernel.org/stable/c/66959ed481a474eaae278c7f6860a2a9b188a4d6"
        },
        {
          "url": "https://git.kernel.org/stable/c/ef06fd16d48704eac868441d98d4ef083d8f3d07"
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-23383",
    "datePublished": "2026-03-25T10:28:02.126Z",
    "dateReserved": "2026-01-13T15:37:46.007Z",
    "dateUpdated": "2026-04-02T14:44:28.675Z",
    "state": "PUBLISHED"
  },
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  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-23383\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-03-25T11:16:38.487\",\"lastModified\":\"2026-04-02T15:16:32.693\",\"vulnStatus\":\"Awaiting Analysis\",\"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\u0027d 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 alineaci\u00f3n de 8 bytes para el b\u00fafer JIT para prevenir el desgarro at\u00f3mico\\n\\nstruct bpf_plt contiene un campo objetivo u64. Actualmente, el asignador JIT de BPF solicita una alineaci\u00f3n de 4 bytes (sizeof(u32)) para el b\u00fafer JIT.\\n\\nDebido a que la direcci\u00f3n base del b\u00fafer JIT puede estar alineada a 4 bytes (p. ej., terminando en 0x4 o 0xc), la l\u00f3gica de relleno relativo en build_plt() no logra asegurar que target caiga en un l\u00edmite de 8 bytes.\\n\\nEsto lleva a dos problemas:\\n1. UBSAN informa advertencias de acceso desalineado al desreferenciar la estructura.\\n2. M\u00e1s cr\u00edticamente, target se actualiza concurrentemente a trav\u00e9s de WRITE_ONCE() en bpf_arch_text_poke() mientras el c\u00f3digo JIT\u0027d ejecuta ldr. En arm64, las cargas/almacenamientos de 64 bits solo se garantiza que sean at\u00f3micos de copia \u00fanica si est\u00e1n alineados a 64 bits. Un target desalineado arriesga una lectura desgarrada, haciendo que el JIT salte a una direcci\u00f3n corrupta.\\n\\nSolucione esto aumentando el requisito de alineaci\u00f3n de asignaci\u00f3n a 8 bytes (sizeof(u64)) en bpf_jit_binary_pack_alloc(). Esto ancla la base del b\u00fafer JIT a un l\u00edmite de 8 bytes, permitiendo que las matem\u00e1ticas 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}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/519b1ad91de5bf7a496f2b858e9212db6328e1de\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/66959ed481a474eaae278c7f6860a2a9b188a4d6\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/80ad264da02cc4aee718e799c2b79f0f834673dc\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/ef06fd16d48704eac868441d98d4ef083d8f3d07\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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