{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2021-46908", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-02-25T13:45:52.718Z", "datePublished": "2024-02-27T06:53:49.541Z", "dateUpdated": "2026-08-05T08:44:59.893Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T08:44:59.893Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Use correct permission flag for mixed signed bounds arithmetic\n\nWe forbid adding unknown scalars with mixed signed bounds due to the\nspectre v1 masking mitigation. Hence this also needs bypass_spec_v1\nflag instead of allow_ptr_leaks." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H", "baseScore": 7.1, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The vulnerable code is in the BPF verifier (adjust_ptr_min_max_vals), reached only via the local bpf() syscall when loading a program (e.g. SOCKET_FILTER), not via network packet processing.\nAC:L - An attacker can reliably craft and load a BPF program with mixed signed-bounds pointer arithmetic on PTR_TO_MAP_VALUE; no race or external environmental condition beyond the attacker's control is required to reach the buggy check. Unprivileged users can load BPF_PROG_TYPE_SOCKET_FILTER/CGROUP_SKB when kernel.unprivileged_bpf_disabled is 0 (upstream default throughout the 5.8–5.11 affected range), which exercises this verifier path without CAP_BPF or CAP_PERFMON. An attacker can reliably craft and load a BPF program with mixed signed-bounds pointer arithmetic on PTR_TO_MAP_VALUE; no race or external environmental condition beyond the attacker's control is required to reach the buggy check.\nPR:L - Unprivileged users can load BPF_PROG_TYPE_SOCKET_FILTER/CGROUP_SKB when kernel.unprivileged_bpf_disabled is 0 (upstream default throughout the 5.8–5.11 affected range), which exercises this verifier path without CAP_BPF or CAP_PERFMON.\nUI:N - Exploitation requires only the attacker loading their own BPF program; no victim action is needed.\nS:U - Impact stays within the kernel's security authority (local speculative disclosure of kernel memory); this is not a VM/IOMMU/sandbox boundary crossing.\nC:H - The check exists specifically for Spectre v1 masking of map-value pointer arithmetic; bypassing it enables speculative out-of-bounds access that can disclose arbitrary kernel memory via side channels, matching other BPF Spectre CVEs.\nI:N - This is a speculative-execution mitigation gap; architectural verifier bounds still apply and speculative effects do not commit writes, so integrity is not impacted.\nA:H - Same-series BPF Spectre sanitation bugs (e.g. CVE-2020-27171) and existing assessments of this CVE treat failed/incorrect ALU sanitation as potentially crashing the kernel; under the overestimate rule A:H is the higher-severity choice." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "kernel/bpf/verifier.c" ], "versions": [ { "version": "2c78ee898d8f10ae6fb2fa23a3fbaec96b1b7366", "lessThan": "4f3ff11204eac0ee23acf64deecb3bad7b0db0c6", "status": "affected", "versionType": "git" }, { "version": "2c78ee898d8f10ae6fb2fa23a3fbaec96b1b7366", "lessThan": "4ccdc6c6cae38b91c871293fb0ed8c6845a61b51", "status": "affected", "versionType": "git" }, { "version": "2c78ee898d8f10ae6fb2fa23a3fbaec96b1b7366", "lessThan": "9601148392520e2e134936e76788fc2a6371e7be", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "kernel/bpf/verifier.c" ], "versions": [ { "version": "5.8", "status": "affected" }, { "version": "0", "lessThan": "5.8", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.32", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.11.16", "lessThanOrEqual": "5.11.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.12", "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": "5.8", "versionEndExcluding": "5.10.32" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.8", "versionEndExcluding": "5.11.16" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.8", "versionEndExcluding": "5.12" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/4f3ff11204eac0ee23acf64deecb3bad7b0db0c6" }, { "url": "https://git.kernel.org/stable/c/4ccdc6c6cae38b91c871293fb0ed8c6845a61b51" }, { "url": "https://git.kernel.org/stable/c/9601148392520e2e134936e76788fc2a6371e7be" } ], "title": "bpf: Use correct permission flag for mixed signed bounds arithmetic", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "title": "CISA ADP Vulnrichment", "metrics": [ { "other": { "type": "ssvc", "content": { "id": "CVE-2021-46908", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "partial" } ], "version": "2.0.3", "timestamp": "2024-02-27T15:41:34.586719Z" } } } ], "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2024-06-04T17:13:12.609Z" } }, { "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2024-08-04T05:17:43.036Z" }, "title": "CVE Program Container", "references": [ { "url": "https://git.kernel.org/stable/c/4f3ff11204eac0ee23acf64deecb3bad7b0db0c6", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/4ccdc6c6cae38b91c871293fb0ed8c6845a61b51", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/9601148392520e2e134936e76788fc2a6371e7be", "tags": [ "x_transferred" ] } ] } ] } }