{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2024-40909", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-07-12T12:17:45.580Z", "datePublished": "2024-07-12T12:20:48.447Z", "dateUpdated": "2026-08-05T11:33:56.691Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:33:56.691Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix a potential use-after-free in bpf_link_free()\n\nAfter commit 1a80dbcb2dba, bpf_link can be freed by\nlink->ops->dealloc_deferred, but the code still tests and uses\nlink->ops->dealloc afterward, which leads to a use-after-free as\nreported by syzbot. Actually, one of them should be sufficient, so\njust call one of them instead of both. Also add a WARN_ON() in case\nof any problematic implementation." } ], "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 vulnerability is reached exclusively through the local `bpf()` syscall — creating a raw_tracepoint/kprobe_multi/uprobe_multi link and then closing its file descriptor. No network or remote-peer data is involved.\nAC:L - The attacker drives the free side directly and can repeat the create/close cycle in an unbounded loop across all CPUs while generating scheduling and RCU load to force preemption between `call_rcu()` and the stale `link->ops` read; syzbot triggered it in practice, so the window is reachable without relying on conditions outside attacker influence.\nPR:L - `bpf_token_capable()` grants BPF/PERFMON at `ns_capable()` level when a BPF token is delegated (kernel/bpf/token.c:17-28), so a process unprivileged in the init namespace inside a container can load these tracing programs and create the affected links; the same path is reachable by ordinary non-root service accounts holding only CAP_BPF+CAP_PERFMON, which is not administrative control of the host.\nUI:N - The entire sequence — link creation and fd close — is performed by the attacker's own process with no action required from any other user.\nS:U - The corruption and its consequences are confined to the kernel's own memory and privilege domain; no hypervisor, IOMMU, or other security-authority boundary is crossed.\nC:H - The use-after-free reads the `ops` pointer out of a freed slab object that the attacker can reallocate and fill via heap spraying, yielding an arbitrary kernel pointer dereference and an arbitrary-read primitive over kernel memory.\nI:H - After the stale `link->ops` read, the code performs `link->ops->dealloc(link)` — an indirect call through an attacker-controlled function pointer table, giving control-flow hijack and full kernel-integrity compromise.\nA:H - Even unweaponized, dereferencing and calling through a freed/recycled `ops` pointer produces a wild indirect branch and immediate kernel oops or panic, and the attacker can trigger it repeatedly." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "kernel/bpf/syscall.c" ], "versions": [ { "version": "876941f533e7b47fc69977fc4551c02f2d18af97", "lessThan": "91cff53136daeff50816b0baeafd38a6976f6209", "status": "affected", "versionType": "git" }, { "version": "1a80dbcb2dbaf6e4c216e62e30fa7d3daa8001ce", "lessThan": "fa97b8fed9896f1e89cb657513e483a152d4c382", "status": "affected", "versionType": "git" }, { "version": "1a80dbcb2dbaf6e4c216e62e30fa7d3daa8001ce", "lessThan": "2884dc7d08d98a89d8d65121524bb7533183a63a", "status": "affected", "versionType": "git" }, { "version": "5d8d447777564b35f67000e7838e7ccb64d525c8", "status": "affected", "versionType": "git" }, { "version": "6.6.26", "lessThan": "6.6.35", "status": "affected", "versionType": "semver" }, { "version": "6.8.5", "lessThan": "6.9", "status": "affected", "versionType": "semver" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "kernel/bpf/syscall.c" ], "versions": [ { "version": "6.9", "status": "affected" }, { "version": "0", "lessThan": "6.9", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.35", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.9.6", "lessThanOrEqual": "6.9.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.10", "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": "6.6.26", "versionEndExcluding": "6.6.35" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.9", "versionEndExcluding": "6.9.6" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.9", "versionEndExcluding": "6.10" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.8.5" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/91cff53136daeff50816b0baeafd38a6976f6209" }, { "url": "https://git.kernel.org/stable/c/fa97b8fed9896f1e89cb657513e483a152d4c382" }, { "url": "https://git.kernel.org/stable/c/2884dc7d08d98a89d8d65121524bb7533183a63a" } ], "title": "bpf: Fix a potential use-after-free in bpf_link_free()", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2024-08-02T04:39:55.487Z" }, "title": "CVE Program Container", "references": [ { "url": "https://git.kernel.org/stable/c/91cff53136daeff50816b0baeafd38a6976f6209", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/fa97b8fed9896f1e89cb657513e483a152d4c382", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/2884dc7d08d98a89d8d65121524bb7533183a63a", "tags": [ "x_transferred" ] } ] }, { "metrics": [ { "other": { "type": "ssvc", "content": { "id": "CVE-2024-40909", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "partial" } ], "version": "2.0.3", "timestamp": "2024-09-10T17:06:09.099919Z" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2024-09-11T17:34:37.410Z" } } ] } }