{"id":"CVE-2026-98378","state":"PUBLISHED","title":"bpf: Skip unsettled links in link iterator","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Skip unsettled links in link iterator\n\nbpf_link_prime() inserts a link into link_idr before anon_inode_getfile()\nsucceeds and before bpf_link_settle() publishes the ID in link->id.\nbpf_link_by_id() treats such an ID-zero link as unsettled, but the link\niterator takes a reference without this check.\n\nIf anon_inode_getfile() then fails, the creator removes the ID and frees\nits still-private link directly.  The iterator is left with a dangling\nreference and its next bpf_link_put() accesses freed memory.\n\nTreat ID-zero entries as transient in bpf_link_get_curr_or_next(), just as\nbpf_link_by_id() does.\n\n  BUG: KASAN: slab-use-after-free in bpf_link_put\n  Write of size 8 by task exp/384\n  Call Trace:\n  bpf_link_put                    kernel/bpf/syscall.c:3372\n  bpf_link_seq_next               kernel/bpf/link_iter.c:33\n  bpf_seq_read                    kernel/bpf/bpf_iter.c:158\n  vfs_read                        fs/read_write.c:572\n  ksys_read                       fs/read_write.c:716\n  do_syscall_64                   arch/x86/entry/syscall_64.c:84\n  entry_SYSCALL_64_after_hwframe  arch/x86/entry/entry_64.S:121\n  Kernel panic - not syncing: KASAN: panic_on_warn set ...","publishedAt":"2026-10-09T07:34:18.626Z","updatedAt":"2026-10-24T14:08:37.091Z","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":"9f88361273082825d9f0d13a543d49f9fa0d44a8","status":"affected","lessThan":"68930f8d40ab4c10ca3b019f076136758fd100a8","versionType":"git"},{"version":"9f88361273082825d9f0d13a543d49f9fa0d44a8","status":"affected","lessThan":"c251ed48bd9063cf7de6049421e78b6de989060f","versionType":"git"},{"version":"9f88361273082825d9f0d13a543d49f9fa0d44a8","status":"affected","lessThan":"798a61edbc436cacdb659927d067368eeb1e30e2","versionType":"git"},{"version":"9f88361273082825d9f0d13a543d49f9fa0d44a8","status":"affected","lessThan":"6e271f093d15d323f42de26f66556af53fa8e19f","versionType":"git"},{"version":"9f88361273082825d9f0d13a543d49f9fa0d44a8","status":"affected","lessThan":"87ce4b53b7436b50fc984f0a6afaf77f68ac5573","versionType":"git"},{"version":"9f88361273082825d9f0d13a543d49f9fa0d44a8","status":"affected","lessThan":"50e80e2bb5e2be8515205b9c496b9640ddefa434","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/bpf/syscall.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.19","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.19","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":["kernel/bpf/syscall.c"]}],"references":["https://git.kernel.org/stable/c/68930f8d40ab4c10ca3b019f076136758fd100a8","https://git.kernel.org/stable/c/c251ed48bd9063cf7de6049421e78b6de989060f","https://git.kernel.org/stable/c/798a61edbc436cacdb659927d067368eeb1e30e2","https://git.kernel.org/stable/c/6e271f093d15d323f42de26f66556af53fa8e19f","https://git.kernel.org/stable/c/87ce4b53b7436b50fc984f0a6afaf77f68ac5573","https://git.kernel.org/stable/c/50e80e2bb5e2be8515205b9c496b9640ddefa434"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:43.249Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/98xxx/CVE-2026-98378.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-98378","state":"PUBLISHED","datePublished":"2026-10-09T07:34:18.626Z","dateUpdated":"2026-10-24T14:08:37.091Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-25T10:25:14.345Z"},"containers":{"cna":{"title":"bpf: Skip unsettled links in link iterator","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Skip unsettled links in link iterator\n\nbpf_link_prime() inserts a link into link_idr before anon_inode_getfile()\nsucceeds and before bpf_link_settle() publishes the ID in link->id.\nbpf_link_by_id() treats such an ID-zero link as unsettled, but the link\niterator takes a reference without this check.\n\nIf anon_inode_getfile() then fails, the creator removes the ID and frees\nits still-private link directly.  The iterator is left with a dangling\nreference and its next bpf_link_put() accesses freed memory.\n\nTreat ID-zero entries as transient in bpf_link_get_curr_or_next(), just as\nbpf_link_by_id() does.\n\n  BUG: KASAN: slab-use-after-free in bpf_link_put\n  Write of size 8 by task exp/384\n  Call Trace:\n  bpf_link_put                    kernel/bpf/syscall.c:3372\n  bpf_link_seq_next               kernel/bpf/link_iter.c:33\n  bpf_seq_read                    kernel/bpf/bpf_iter.c:158\n  vfs_read                        fs/read_write.c:572\n  ksys_read                       fs/read_write.c:716\n  do_syscall_64                   arch/x86/entry/syscall_64.c:84\n  entry_SYSCALL_64_after_hwframe  arch/x86/entry/entry_64.S:121\n  Kernel panic - not syncing: KASAN: panic_on_warn set ..."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"9f88361273082825d9f0d13a543d49f9fa0d44a8","status":"affected","lessThan":"68930f8d40ab4c10ca3b019f076136758fd100a8","versionType":"git"},{"version":"9f88361273082825d9f0d13a543d49f9fa0d44a8","status":"affected","lessThan":"c251ed48bd9063cf7de6049421e78b6de989060f","versionType":"git"},{"version":"9f88361273082825d9f0d13a543d49f9fa0d44a8","status":"affected","lessThan":"798a61edbc436cacdb659927d067368eeb1e30e2","versionType":"git"},{"version":"9f88361273082825d9f0d13a543d49f9fa0d44a8","status":"affected","lessThan":"6e271f093d15d323f42de26f66556af53fa8e19f","versionType":"git"},{"version":"9f88361273082825d9f0d13a543d49f9fa0d44a8","status":"affected","lessThan":"87ce4b53b7436b50fc984f0a6afaf77f68ac5573","versionType":"git"},{"version":"9f88361273082825d9f0d13a543d49f9fa0d44a8","status":"affected","lessThan":"50e80e2bb5e2be8515205b9c496b9640ddefa434","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/bpf/syscall.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.19","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.19","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":["kernel/bpf/syscall.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/68930f8d40ab4c10ca3b019f076136758fd100a8"},{"url":"https://git.kernel.org/stable/c/c251ed48bd9063cf7de6049421e78b6de989060f"},{"url":"https://git.kernel.org/stable/c/798a61edbc436cacdb659927d067368eeb1e30e2"},{"url":"https://git.kernel.org/stable/c/6e271f093d15d323f42de26f66556af53fa8e19f"},{"url":"https://git.kernel.org/stable/c/87ce4b53b7436b50fc984f0a6afaf77f68ac5573"},{"url":"https://git.kernel.org/stable/c/50e80e2bb5e2be8515205b9c496b9640ddefa434"}],"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 - Both required paths are local: bpf(BPF_LINK_CREATE/BPF_ITER_CREATE) prepares the bpf_link iterator, and read() reaches bpf_seq_read() -> bpf_link_seq_next() -> the patched bpf_link_get_curr_or_next(); no network data enters this state.\nAC:L - The attacker can fill fs.file-max so anon_inode_getfile() returns -ENFILE, then run the iterator reader and repeated BPF_LINK_CREATE calls concurrently, controlling both sides of the IDR insert/remove race.\nPR:L - BPF_PROG_LOAD for BPF_PROG_TYPE_TRACING/BPF_TRACE_ITER requires CAP_BPF and CAP_PERFMON, but bpf_token_capable() accepts them in a delegated bpffs token's user namespace; this permits a namespace-root local user, while a bare user namespace does not.\nUI:N - After preparing the iterator and program FDs, the attacking process itself issues read() and concurrent BPF_LINK_CREATE calls; no victim action is required.\nS:U - bpf_link_get_curr_or_next() leaves a dangling object inside the same host kernel that services the BPF syscalls; it crosses no guest/host, IOMMU, or separate security authority boundary.\nC:H - The iterator retains a freed struct bpf_link pointer; reclaiming that slab object makes later bpf_link_put()/bpf_link_free() consume attacker-influenced refcnt, ops, and prog fields, supporting kernel-memory disclosure.\nI:H - bpf_link_put() performs atomic64_dec_and_test() on the freed object's first eight bytes and can initialize and queue its reclaimed work_struct, so controlled reuse supports arbitrary corruption or control-flow hijacking.\nA:H - The demonstrated read() path reaches bpf_link_seq_next() and bpf_link_put() after the link is freed, producing a KASAN use-after-free and kernel panic; the same stale write can crash a non-KASAN kernel."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-24T14:08:37.091Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.19","versionEndExcluding":"6.1.189"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.19","versionEndExcluding":"6.6.158"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.19","versionEndExcluding":"6.12.112"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.19","versionEndExcluding":"6.18.55"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.19","versionEndExcluding":"7.2.9"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.19","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}