{"id":"CVE-2026-98383","state":"PUBLISHED","title":"bpf: Disallow bpf_skb_pull_data() for LWT_SEG6LOCAL","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Disallow bpf_skb_pull_data() for LWT_SEG6LOCAL\n\nAn LWT_SEG6LOCAL program can invalidate its cached SRH with\nbpf_lwt_seg6_adjust_srh() and then call bpf_skb_pull_data(). The latter\nmay reallocate skb->head, leaving the per-CPU SRH pointer dangling.\nPost-program SRH validation then writes through that pointer.\n\nDisallow bpf_skb_pull_data() for LWT_SEG6LOCAL programs so the verifier\nrejects this unsafe helper combination. Other LWT program types continue\nto expose the helper through lwt_out_func_proto().","publishedAt":"2026-10-09T07:34:22.408Z","updatedAt":"2026-10-24T14:08:40.964Z","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":"004d4b274e2a1a895a0e5dc66158b90a7d463d44","status":"affected","lessThan":"0f38472a2aa8704a6b514c0dfa9c32f3672b8f32","versionType":"git"},{"version":"004d4b274e2a1a895a0e5dc66158b90a7d463d44","status":"affected","lessThan":"cae8674489f26edf7553fdd660599466cbb4c32f","versionType":"git"},{"version":"004d4b274e2a1a895a0e5dc66158b90a7d463d44","status":"affected","lessThan":"9f9e57b5a3a033f95f49ef9d541340cdbcb80abb","versionType":"git"},{"version":"004d4b274e2a1a895a0e5dc66158b90a7d463d44","status":"affected","lessThan":"df0072be6fc373cb22f9ea854d458b04e32a03cf","versionType":"git"},{"version":"004d4b274e2a1a895a0e5dc66158b90a7d463d44","status":"affected","lessThan":"b9bb0e735460751b620156f800a4279a28573392","versionType":"git"},{"version":"004d4b274e2a1a895a0e5dc66158b90a7d463d44","status":"affected","lessThan":"37b18688cd18fd86d2f35c212df1611862a26cd5","versionType":"git"},{"version":"004d4b274e2a1a895a0e5dc66158b90a7d463d44","status":"affected","lessThan":"fca71ead7a20290af1e2046983eeafae43d21af1","versionType":"git"},{"version":"004d4b274e2a1a895a0e5dc66158b90a7d463d44","status":"affected","lessThan":"e4a62833adff6ef0fe7c0b90393204fe3c26b5c5","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/core/filter.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.18","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.18","versionType":"semver"},{"version":"5.10.271","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.222","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.189","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.158","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.112","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.55","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.9","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":["net/core/filter.c"]}],"references":["https://git.kernel.org/stable/c/0f38472a2aa8704a6b514c0dfa9c32f3672b8f32","https://git.kernel.org/stable/c/cae8674489f26edf7553fdd660599466cbb4c32f","https://git.kernel.org/stable/c/9f9e57b5a3a033f95f49ef9d541340cdbcb80abb","https://git.kernel.org/stable/c/df0072be6fc373cb22f9ea854d458b04e32a03cf","https://git.kernel.org/stable/c/b9bb0e735460751b620156f800a4279a28573392","https://git.kernel.org/stable/c/37b18688cd18fd86d2f35c212df1611862a26cd5","https://git.kernel.org/stable/c/fca71ead7a20290af1e2046983eeafae43d21af1","https://git.kernel.org/stable/c/e4a62833adff6ef0fe7c0b90393204fe3c26b5c5"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:43.249Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/98xxx/CVE-2026-98383.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-98383","state":"PUBLISHED","datePublished":"2026-10-09T07:34:22.408Z","dateUpdated":"2026-10-24T14:08:40.964Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-25T10:25:14.345Z"},"containers":{"cna":{"title":"bpf: Disallow bpf_skb_pull_data() for LWT_SEG6LOCAL","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Disallow bpf_skb_pull_data() for LWT_SEG6LOCAL\n\nAn LWT_SEG6LOCAL program can invalidate its cached SRH with\nbpf_lwt_seg6_adjust_srh() and then call bpf_skb_pull_data(). The latter\nmay reallocate skb->head, leaving the per-CPU SRH pointer dangling.\nPost-program SRH validation then writes through that pointer.\n\nDisallow bpf_skb_pull_data() for LWT_SEG6LOCAL programs so the verifier\nrejects this unsafe helper combination. Other LWT program types continue\nto expose the helper through lwt_out_func_proto()."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"004d4b274e2a1a895a0e5dc66158b90a7d463d44","status":"affected","lessThan":"0f38472a2aa8704a6b514c0dfa9c32f3672b8f32","versionType":"git"},{"version":"004d4b274e2a1a895a0e5dc66158b90a7d463d44","status":"affected","lessThan":"cae8674489f26edf7553fdd660599466cbb4c32f","versionType":"git"},{"version":"004d4b274e2a1a895a0e5dc66158b90a7d463d44","status":"affected","lessThan":"9f9e57b5a3a033f95f49ef9d541340cdbcb80abb","versionType":"git"},{"version":"004d4b274e2a1a895a0e5dc66158b90a7d463d44","status":"affected","lessThan":"df0072be6fc373cb22f9ea854d458b04e32a03cf","versionType":"git"},{"version":"004d4b274e2a1a895a0e5dc66158b90a7d463d44","status":"affected","lessThan":"b9bb0e735460751b620156f800a4279a28573392","versionType":"git"},{"version":"004d4b274e2a1a895a0e5dc66158b90a7d463d44","status":"affected","lessThan":"37b18688cd18fd86d2f35c212df1611862a26cd5","versionType":"git"},{"version":"004d4b274e2a1a895a0e5dc66158b90a7d463d44","status":"affected","lessThan":"fca71ead7a20290af1e2046983eeafae43d21af1","versionType":"git"},{"version":"004d4b274e2a1a895a0e5dc66158b90a7d463d44","status":"affected","lessThan":"e4a62833adff6ef0fe7c0b90393204fe3c26b5c5","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/core/filter.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.18","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.18","versionType":"semver"},{"version":"5.10.271","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.222","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.189","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.158","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.112","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.55","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.9","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":["net/core/filter.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/0f38472a2aa8704a6b514c0dfa9c32f3672b8f32"},{"url":"https://git.kernel.org/stable/c/cae8674489f26edf7553fdd660599466cbb4c32f"},{"url":"https://git.kernel.org/stable/c/9f9e57b5a3a033f95f49ef9d541340cdbcb80abb"},{"url":"https://git.kernel.org/stable/c/df0072be6fc373cb22f9ea854d458b04e32a03cf"},{"url":"https://git.kernel.org/stable/c/b9bb0e735460751b620156f800a4279a28573392"},{"url":"https://git.kernel.org/stable/c/37b18688cd18fd86d2f35c212df1611862a26cd5"},{"url":"https://git.kernel.org/stable/c/fca71ead7a20290af1e2046983eeafae43d21af1"},{"url":"https://git.kernel.org/stable/c/e4a62833adff6ef0fe7c0b90393204fe3c26b5c5"}],"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 local bpf(BPF_PROG_LOAD) path reaches check_helper_call() and the patched lwt_seg6local_func_proto(), where attacker-authored bytecode requests bpf_lwt_seg6_adjust_srh() and bpf_skb_pull_data(); an RTM_NEWROUTE then attaches it. A received SRH packet merely executes that installed program and cannot create the unsafe helper sequence.\nAC:L - The attacker controls the helper order, SRH offset and length, and can inject a large non-linear SRv6 frame so bpf_skb_pull_data() deterministically reaches __pskb_pull_tail() and pskb_expand_head(). No race is required, and repeated packets reproduce the stale-pointer write.\nPR:L - bpf_prog_load() requires CAP_BPF and CAP_NET_ADMIN for BPF_PROG_TYPE_LWT_SEG6LOCAL, but BPF_F_TOKEN_FD and bpf_token_capable() support delegating both into a user namespace; rtnetlink_rcv_msg() separately accepts CAP_NET_ADMIN in the route's network namespace. Thus a host-unprivileged token holder can perform the complete setup.\nUI:N - The attacker loads the program, installs the End.BPF route, and injects the triggering SRv6 frame without any victim action.\nS:U - The stale srh pointer and resulting corruption occur in the same host kernel that processes the attacker's BPF program and packet; no VM, IOMMU, or other security-authority boundary is crossed.\nC:H - After skb->head is freed, seg6_bpf_has_valid_srh() passes the dangling srh pointer to seg6_validate_srh(), which reads header fields and variable-length TLVs from reusable slab memory; its drop-versus-forward result also provides an observable contents oracle.\nI:H - seg6_bpf_has_valid_srh() executes srh->hdrlen = srh_state->hdrlen >> 3 through the dangling pointer, producing an attacker-valued one-byte write into freed slab memory that can corrupt a reclaimed object or allocator state and support control-flow compromise.\nA:H - The stale write in seg6_bpf_has_valid_srh() is a confirmed slab use-after-free and can trigger a KASAN panic or later kernel oops through corrupted freed-object state; the attacker can repeat it with additional packets."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-24T14:08:40.964Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.18","versionEndExcluding":"5.10.271"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.18","versionEndExcluding":"5.15.222"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.18","versionEndExcluding":"6.1.189"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.18","versionEndExcluding":"6.6.158"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.18","versionEndExcluding":"6.12.112"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.18","versionEndExcluding":"6.18.55"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.18","versionEndExcluding":"7.2.9"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.18","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}