{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-74314", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-15T05:44:03.883Z", "datePublished": "2026-08-15T05:58:12.766Z", "dateUpdated": "2026-08-17T05:45:47.130Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-17T05:45:47.130Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Cancel special fields on map value recycle\n\nMap update and delete paths currently call bpf_obj_free_fields() when a\nvalue is being replaced or recycled. That makes field destruction depend\non the context of the update/delete operation. For tracing programs this\ncan include NMI context, where referenced kptr destructors, uptr\nunpinning, and graph root destruction are not generally safe.\n\nIntroduce bpf_obj_cancel_fields() for the reusable-value path. It only\nperforms NMI-safe cleanup for timer, workqueue, and task_work fields.\nFields that need full destruction are left attached to the recycled value\nand are destroyed by the final cleanup path instead.\n\nSwitch array and hashtab update/delete/recycle paths to this cancel\nhelper. Keep bpf_obj_free_fields() for final map destruction and for\nbpf_mem_alloc destructors. Preallocated hashtabs do not have allocator\ndestructors, so teardown continues to walk the normal and extra elements\nand fully destroy their fields.\n\nThis deliberately relaxes the eager-free semantics of map update/delete\nfor special fields. Programs that relied on a recycled map slot becoming\nempty immediately after update/delete were relying on behavior that\ncannot be implemented safely from every BPF execution context without\noffloading arbitrary destructors.\n\nThere is a chance this change breaks programs making assumptions\nregarding the eager freeing of fields. If so, we can relax semantics to\ncancellation only when irqs_disabled() is true in the future. However,\ntheoretically, map values that get reused eagerly already have weaker\nguarantees as parallel users can recreate freed fields before the new\nelement becomes visible again." } ], "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 bug is reached via bpf_map_update_elem/delete_elem on BPF array/hash maps, callable from the bpf() syscall and from in-kernel BPF helpers when tracing or perf BPF programs run; per kernel guidance BPF is a Local attack vector, not network-reachable.\nAC:L - An attacker who can load and attach BPF programs controls the map contents, update/delete timing, and trace/perf attach points (including NMI-capable hooks), so the unsafe bpf_obj_free_fields() recycle path is triggerable without luck or victim-specific state.\nPR:L - Exploitation requires loading tracing/perf BPF programs with BTF maps holding kptr/list/uptr fields (CAP_BPF plus CAP_PERFMON), which bpf_token_capable() grants to user-namespace CAP_SYS_ADMIN holders (e.g. unshare -Urn) and delegated BPF token users, not only init-namespace root.\nUI:N - No victim interaction is required; the attacker triggers map recycle from their own loaded BPF program or concurrent bpf() map operations during tracing/perf events they control.\nS:U - Impact stays within kernel memory and privilege boundaries (deadlock, oops, memory corruption, potential local privilege escalation) and does not cross VM, container, or IOMMU security scopes on its own.\nC:H - Recycling map values from NMI/atomic tracing context runs bpf_obj_free_fields() kptr destructors, uptr unpinning, and graph teardown unsafely, enabling use-after-free and inconsistent object lifetimes that can be turned into arbitrary kernel memory disclosure.\nI:H - The same unsafe recycle path performs non-NMI-safe kptr destructor calls, recursive __bpf_obj_drop_impl() graph freeing, and uptr unpinning from wrong context, giving plausible heap corruption and control-flow hijack primitives beyond a simple crash.\nA:H - Calling bpf_obj_free_fields() from NMI/tracing contexts can deadlock on BPF/hash locks (documented IN-NMI lockdep failures in related BPF LRU fixes) or panic/oops via illegal page unpinning and destructor execution, fully denying kernel availability." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "include/linux/bpf.h", "kernel/bpf/arraymap.c", "kernel/bpf/hashtab.c", "kernel/bpf/syscall.c", "tools/testing/selftests/bpf/prog_tests/htab_update.c", "tools/testing/selftests/bpf/prog_tests/linked_list.c", "tools/testing/selftests/bpf/prog_tests/map_kptr.c", "tools/testing/selftests/bpf/prog_tests/refcounted_kptr.c", "tools/testing/selftests/bpf/progs/htab_update.c", "tools/testing/selftests/bpf/progs/linked_list.c", "tools/testing/selftests/bpf/progs/refcounted_kptr.c" ], "versions": [ { "version": "14a324f6a67ef6a53e04362a70160a47eb8afffa", "lessThan": "9ea734e2cc0143d7429ab7dc0b20c85e5836183c", "status": "affected", "versionType": "git" }, { "version": "14a324f6a67ef6a53e04362a70160a47eb8afffa", "lessThan": "a3a81d247651218e47153f2d2afd7aee236726fd", "status": "affected", "versionType": "git" }, { "version": "f0462d38589422bc9e27fd3c6343dfeb6b3db2f9", "status": "affected", "versionType": "git" }, { "version": "5.18.18", "lessThan": "5.19", "status": "affected", "versionType": "semver" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "include/linux/bpf.h", "kernel/bpf/arraymap.c", "kernel/bpf/hashtab.c", "kernel/bpf/syscall.c", "tools/testing/selftests/bpf/prog_tests/htab_update.c", "tools/testing/selftests/bpf/prog_tests/linked_list.c", "tools/testing/selftests/bpf/prog_tests/map_kptr.c", "tools/testing/selftests/bpf/prog_tests/refcounted_kptr.c", "tools/testing/selftests/bpf/progs/htab_update.c", "tools/testing/selftests/bpf/progs/linked_list.c", "tools/testing/selftests/bpf/progs/refcounted_kptr.c" ], "versions": [ { "version": "5.19", "status": "affected" }, { "version": "0", "lessThan": "5.19", "status": "unaffected", "versionType": "semver" }, { "version": "7.1.5", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "7.1.5" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "7.2" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.18.18" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/9ea734e2cc0143d7429ab7dc0b20c85e5836183c" }, { "url": "https://git.kernel.org/stable/c/a3a81d247651218e47153f2d2afd7aee236726fd" } ], "title": "bpf: Cancel special fields on map value recycle", "x_generator": { "engine": "bippy-1.2.0" } } } }