{"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"]}]}]}}