{"id":"CVE-2026-93144","state":"PUBLISHED","title":"bpf: Reject writes through untrusted BTF pointers","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Reject writes through untrusted BTF pointers\n\ncheck_ptr_to_btf_access() lets program-type btf_struct_access callbacks\nvalidate writes before the default BTF access path rejects non-read\naccesses. That bypasses the read-only policy for untrusted BTF pointers\ncreated by helpers such as bpf_rdonly_cast().\n\nReject non-read accesses through PTR_UNTRUSTED BTF pointers at the\ncommon entry point, before the callback branch to handle all cases.","publishedAt":"2026-09-17T16:11:42.757Z","updatedAt":"2026-10-21T12:52:02.003Z","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":"282de143ead96a5d53331e946f31c977b4610a74","status":"affected","lessThan":"56f92fecd80419567288b7972caa90107033836e","versionType":"git"},{"version":"282de143ead96a5d53331e946f31c977b4610a74","status":"affected","lessThan":"c4dc883447ae38c4e22a29cc016046fa65d88994","versionType":"git"},{"version":"282de143ead96a5d53331e946f31c977b4610a74","status":"affected","lessThan":"644cf4e77c2770d4246f6d12f99bc80d253b0ec6","versionType":"git"},{"version":"282de143ead96a5d53331e946f31c977b4610a74","status":"affected","lessThan":"19d5566b84ca1af0256d0d0003e1a081580c3ba3","versionType":"git"},{"version":"282de143ead96a5d53331e946f31c977b4610a74","status":"affected","lessThan":"ac65c710cc643cbc52b899627577357867249530","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/bpf/verifier.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.2","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.2","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.114","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.57","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.6","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/bpf/verifier.c"]}],"references":["https://git.kernel.org/stable/c/56f92fecd80419567288b7972caa90107033836e","https://git.kernel.org/stable/c/c4dc883447ae38c4e22a29cc016046fa65d88994","https://git.kernel.org/stable/c/644cf4e77c2770d4246f6d12f99bc80d253b0ec6","https://git.kernel.org/stable/c/19d5566b84ca1af0256d0d0003e1a081580c3ba3","https://git.kernel.org/stable/c/ac65c710cc643cbc52b899627577357867249530"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:34.582Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/93xxx/CVE-2026-93144.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-93144","state":"PUBLISHED","datePublished":"2026-09-17T16:11:42.757Z","dateUpdated":"2026-10-21T12:52:02.003Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-17T16:02:15.088Z"},"containers":{"cna":{"title":"bpf: Reject writes through untrusted BTF pointers","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Reject writes through untrusted BTF pointers\n\ncheck_ptr_to_btf_access() lets program-type btf_struct_access callbacks\nvalidate writes before the default BTF access path rejects non-read\naccesses. That bypasses the read-only policy for untrusted BTF pointers\ncreated by helpers such as bpf_rdonly_cast().\n\nReject non-read accesses through PTR_UNTRUSTED BTF pointers at the\ncommon entry point, before the callback branch to handle all cases."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"282de143ead96a5d53331e946f31c977b4610a74","status":"affected","lessThan":"56f92fecd80419567288b7972caa90107033836e","versionType":"git"},{"version":"282de143ead96a5d53331e946f31c977b4610a74","status":"affected","lessThan":"c4dc883447ae38c4e22a29cc016046fa65d88994","versionType":"git"},{"version":"282de143ead96a5d53331e946f31c977b4610a74","status":"affected","lessThan":"644cf4e77c2770d4246f6d12f99bc80d253b0ec6","versionType":"git"},{"version":"282de143ead96a5d53331e946f31c977b4610a74","status":"affected","lessThan":"19d5566b84ca1af0256d0d0003e1a081580c3ba3","versionType":"git"},{"version":"282de143ead96a5d53331e946f31c977b4610a74","status":"affected","lessThan":"ac65c710cc643cbc52b899627577357867249530","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/bpf/verifier.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.2","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.2","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.114","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.57","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.6","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/bpf/verifier.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/56f92fecd80419567288b7972caa90107033836e"},{"url":"https://git.kernel.org/stable/c/c4dc883447ae38c4e22a29cc016046fa65d88994"},{"url":"https://git.kernel.org/stable/c/644cf4e77c2770d4246f6d12f99bc80d253b0ec6"},{"url":"https://git.kernel.org/stable/c/19d5566b84ca1af0256d0d0003e1a081580c3ba3"},{"url":"https://git.kernel.org/stable/c/ac65c710cc643cbc52b899627577357867249530"}],"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 - The attacker-controlled input is BPF bytecode that calls bpf_rdonly_cast() then STX, submitted via bpf(BPF_PROG_LOAD) in SYSCALL_DEFINE5(bpf) → bpf_prog_load() → bpf_check() → do_check_main() → check_mem_access() → check_ptr_to_btf_access(); no remote protocol carries that untrusted pointer or the store.\nAC:L - A BPF_PROG_TYPE_STRUCT_OPS program attached to bpf_dummy_ops (check_struct_ops_btf_id() sets env->ops to bpf_dummy_ops_btf_struct_access) or a BPF_PROG_TYPE_SCHED_CLS program (tc_cls_act_btf_struct_access) does bpf_rdonly_cast() then a store; the WRITE path ran the callback before the old \"only read is supported\" check. No race.\nPR:L - check_ptr_to_btf_access() returns -EPERM unless env->allow_ptr_leaks (bpf_token_capable(CAP_PERFMON)); STRUCT_OPS also fails is_perfmon_prog_type() without CAP_PERFMON, and add_subprog_and_kfunc() needs env->bpf_capable to emit bpf_rdonly_cast. bpf_token_capable() uses ns_capable() on a delegated token userns, not init-namespace root.\nUI:N - The attacker loads that program with BPF_PROG_LOAD and runs it via BPF_PROG_TEST_RUN (bpf_struct_ops_test_run() → dummy_ops_call_op() for bpf_dummy_ops, or bpf_prog_test_run_skb() for SCHED_CLS). No other user must mount, open a file, or cooperate.\nS:U - bpf_convert_ctx_accesses() leaves PTR_TO_BTF_ID|PTR_UNTRUSTED stores as plain STX (only reads become BPF_PROBE_MEM), so the write corrupts host kernel memory in the same authority as the bpf() caller; this is not a KVM/Xen guest-to-host escape or IOMMU bypass.\nC:H - The accepted STX writes attacker bytes through a bpf_rdonly_cast() pointer (obj__ign skips type checks) at bpf_dummy_ops_state.val, nf_conn.mark, or tcp_sock.snd_cwnd. That type-confused kernel write is a memory-corruption primitive that can be turned into an arbitrary kernel read.\nI:H - bpf_dummy_ops_btf_struct_access() accepts any store within sizeof(struct bpf_dummy_ops_state), and _nf_conntrack_btf_struct_access() accepts nf_conn.mark, on a PTR_UNTRUSTED base from bpf_rdonly_cast(); the JIT emits a plain store to that address, an arbitrary kernel write usable for control-flow hijacking.\nA:H - The same unprobed STX to bpf_rdonly_cast(0, btf_id) or to an out-of-bounds map/stack address page-faults in kernel context during bpf_struct_ops_test_run()/bpf_prog_test_run_skb() and oopses/panics, and the attacker can repeat BPF_PROG_TEST_RUN at will."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-21T12:52:02.003Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.2","versionEndExcluding":"6.6.160"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.2","versionEndExcluding":"6.12.114"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.2","versionEndExcluding":"6.18.57"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.2","versionEndExcluding":"7.2.6"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.2","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}