{"id":"CVE-2026-23383","state":"PUBLISHED","title":"bpf, arm64: Force 8-byte alignment for JIT buffer to prevent atomic tearing","description":"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.","publishedAt":"2026-03-25T10:28:02.126Z","updatedAt":"2026-10-30T12:24:03.405Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"b2ad54e1533e91449cb2a371e034942bd7882b58","status":"affected","lessThan":"fcb9c6275f712860c22c96a472b73d05cabb75cd","versionType":"git"},{"version":"b2ad54e1533e91449cb2a371e034942bd7882b58","status":"affected","lessThan":"f5a41b61b5faae1965a5a2cb55322fe8f17e3b2d","versionType":"git"},{"version":"b2ad54e1533e91449cb2a371e034942bd7882b58","status":"affected","lessThan":"80ad264da02cc4aee718e799c2b79f0f834673dc","versionType":"git"},{"version":"b2ad54e1533e91449cb2a371e034942bd7882b58","status":"affected","lessThan":"519b1ad91de5bf7a496f2b858e9212db6328e1de","versionType":"git"},{"version":"b2ad54e1533e91449cb2a371e034942bd7882b58","status":"affected","lessThan":"66959ed481a474eaae278c7f6860a2a9b188a4d6","versionType":"git"},{"version":"b2ad54e1533e91449cb2a371e034942bd7882b58","status":"affected","lessThan":"ef06fd16d48704eac868441d98d4ef083d8f3d07","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/arm64/net/bpf_jit_comp.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.0","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.0","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.77","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.17","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.7","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/arm64/net/bpf_jit_comp.c"]}],"references":["https://git.kernel.org/stable/c/fcb9c6275f712860c22c96a472b73d05cabb75cd","https://git.kernel.org/stable/c/f5a41b61b5faae1965a5a2cb55322fe8f17e3b2d","https://git.kernel.org/stable/c/80ad264da02cc4aee718e799c2b79f0f834673dc","https://git.kernel.org/stable/c/519b1ad91de5bf7a496f2b858e9212db6328e1de","https://git.kernel.org/stable/c/66959ed481a474eaae278c7f6860a2a9b188a4d6","https://git.kernel.org/stable/c/ef06fd16d48704eac868441d98d4ef083d8f3d07"],"weaknesses":[],"ingestedAt":"2026-10-30T12:40:04.423Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/23xxx/CVE-2026-23383.json","commit":"db8103c5921aac81d5d90efcf3745980dafabf49","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-23383","state":"PUBLISHED","datePublished":"2026-03-25T10:28:02.126Z","dateUpdated":"2026-10-30T12:24:03.405Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-01-13T15:37:46.007Z"},"containers":{"cna":{"title":"bpf, arm64: Force 8-byte alignment for JIT buffer to prevent atomic tearing","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."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"b2ad54e1533e91449cb2a371e034942bd7882b58","status":"affected","lessThan":"fcb9c6275f712860c22c96a472b73d05cabb75cd","versionType":"git"},{"version":"b2ad54e1533e91449cb2a371e034942bd7882b58","status":"affected","lessThan":"f5a41b61b5faae1965a5a2cb55322fe8f17e3b2d","versionType":"git"},{"version":"b2ad54e1533e91449cb2a371e034942bd7882b58","status":"affected","lessThan":"80ad264da02cc4aee718e799c2b79f0f834673dc","versionType":"git"},{"version":"b2ad54e1533e91449cb2a371e034942bd7882b58","status":"affected","lessThan":"519b1ad91de5bf7a496f2b858e9212db6328e1de","versionType":"git"},{"version":"b2ad54e1533e91449cb2a371e034942bd7882b58","status":"affected","lessThan":"66959ed481a474eaae278c7f6860a2a9b188a4d6","versionType":"git"},{"version":"b2ad54e1533e91449cb2a371e034942bd7882b58","status":"affected","lessThan":"ef06fd16d48704eac868441d98d4ef083d8f3d07","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/arm64/net/bpf_jit_comp.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.0","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.0","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.77","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.17","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.7","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/arm64/net/bpf_jit_comp.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/fcb9c6275f712860c22c96a472b73d05cabb75cd"},{"url":"https://git.kernel.org/stable/c/f5a41b61b5faae1965a5a2cb55322fe8f17e3b2d"},{"url":"https://git.kernel.org/stable/c/80ad264da02cc4aee718e799c2b79f0f834673dc"},{"url":"https://git.kernel.org/stable/c/519b1ad91de5bf7a496f2b858e9212db6328e1de"},{"url":"https://git.kernel.org/stable/c/66959ed481a474eaae278c7f6860a2a9b188a4d6"},{"url":"https://git.kernel.org/stable/c/ef06fd16d48704eac868441d98d4ef083d8f3d07"}],"metrics":[{"cvssV3_1":{"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"},"scenarios":[{"lang":"en","value":"AV:L - BPF is accessed via the bpf() syscall, requiring local system access. There is no remote or adjacent network path to trigger BPF program loading or trampoline attachment.\nAC:L - The attacker controls both sides of the race — they load the BPF program (creating the misaligned PLT) and trigger the text_poke (by attaching a trampoline). The ~50% misalignment chance is overcome by loading multiple programs. No conditions beyond attacker control are needed.\nPR:L - While CAP_BPF and CAP_PERFMON are required, the BPF token delegation mechanism allows these capabilities to be granted to users in user namespaces. This is a supported, reasonable deployment scenario for containerized BPF workloads.\nUI:N - No user interaction is required. The attacker independently loads BPF programs and attaches trampolines.\nS:U - The vulnerability results in kernel-level control flow corruption within the same security authority. No VM escape, IOMMU bypass, or sandbox boundary crossing occurs.\nC:H - The torn PLT target causes a kernel-mode jump to a corrupted address, which is a control-flow hijack in kernel context. This could be leveraged to read arbitrary kernel memory through code execution.\nI:H - A kernel-mode jump to a corrupted address constitutes control-flow hijacking that could be leveraged for arbitrary code execution in kernel context, enabling arbitrary memory writes.\nA:H - Jumping to a corrupted address in kernel mode will almost certainly cause a kernel panic/oops, resulting in complete denial of service."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-30T12:24:03.405Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.0","versionEndExcluding":"6.1.191"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.0","versionEndExcluding":"6.6.160"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.0","versionEndExcluding":"6.12.77"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.0","versionEndExcluding":"6.18.17"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.0","versionEndExcluding":"6.19.7"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.0","versionEndExcluding":"7.0"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}