{"id":"CVE-2021-47669","state":"PUBLISHED","title":"can: vxcan: vxcan_xmit: fix use after free bug","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ncan: vxcan: vxcan_xmit: fix use after free bug\n\nAfter calling netif_rx_ni(skb), dereferencing skb is unsafe.\nEspecially, the canfd_frame cfd which aliases skb memory is accessed\nafter the netif_rx_ni().","publishedAt":"2025-04-17T18:01:29.979Z","updatedAt":"2026-08-05T08:48:49.266Z","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":"a8f820a380a2a06fc4fe1a54159067958f800929","status":"affected","lessThan":"6d6dcf2399cdd26f7f5426ca8dd8366b7f2ca105","versionType":"git"},{"version":"a8f820a380a2a06fc4fe1a54159067958f800929","status":"affected","lessThan":"9b820875a32a3443d67bfd368e93038354e98052","versionType":"git"},{"version":"a8f820a380a2a06fc4fe1a54159067958f800929","status":"affected","lessThan":"a24476b37167816e6352ca1a2cf3769847774f70","versionType":"git"},{"version":"a8f820a380a2a06fc4fe1a54159067958f800929","status":"affected","lessThan":"e771a874076115df8bff27d325edfd2340e4ec69","versionType":"git"},{"version":"a8f820a380a2a06fc4fe1a54159067958f800929","status":"affected","lessThan":"75854cad5d80976f6ea0f0431f8cedd3bcc475cb","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/net/can/vxcan.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.12","versionType":"semver"},{"version":"4.14.218","status":"unaffected","lessThanOrEqual":"4.14.*","versionType":"semver"},{"version":"4.19.171","status":"unaffected","lessThanOrEqual":"4.19.*","versionType":"semver"},{"version":"5.4.93","status":"unaffected","lessThanOrEqual":"5.4.*","versionType":"semver"},{"version":"5.10.11","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.11","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/net/can/vxcan.c"]}],"references":["https://git.kernel.org/stable/c/6d6dcf2399cdd26f7f5426ca8dd8366b7f2ca105","https://git.kernel.org/stable/c/9b820875a32a3443d67bfd368e93038354e98052","https://git.kernel.org/stable/c/a24476b37167816e6352ca1a2cf3769847774f70","https://git.kernel.org/stable/c/e771a874076115df8bff27d325edfd2340e4ec69","https://git.kernel.org/stable/c/75854cad5d80976f6ea0f0431f8cedd3bcc475cb"],"weaknesses":["CWE-416"],"ingestedAt":"2026-10-29T19:49:19.404Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2021/47xxx/CVE-2021-47669.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2021-47669","state":"PUBLISHED","datePublished":"2025-04-17T18:01:29.979Z","dateUpdated":"2026-08-05T08:48:49.266Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2025-04-16T07:16:05.752Z"},"containers":{"cna":{"title":"can: vxcan: vxcan_xmit: fix use after free bug","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ncan: vxcan: vxcan_xmit: fix use after free bug\n\nAfter calling netif_rx_ni(skb), dereferencing skb is unsafe.\nEspecially, the canfd_frame cfd which aliases skb memory is accessed\nafter the netif_rx_ni()."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"a8f820a380a2a06fc4fe1a54159067958f800929","status":"affected","lessThan":"6d6dcf2399cdd26f7f5426ca8dd8366b7f2ca105","versionType":"git"},{"version":"a8f820a380a2a06fc4fe1a54159067958f800929","status":"affected","lessThan":"9b820875a32a3443d67bfd368e93038354e98052","versionType":"git"},{"version":"a8f820a380a2a06fc4fe1a54159067958f800929","status":"affected","lessThan":"a24476b37167816e6352ca1a2cf3769847774f70","versionType":"git"},{"version":"a8f820a380a2a06fc4fe1a54159067958f800929","status":"affected","lessThan":"e771a874076115df8bff27d325edfd2340e4ec69","versionType":"git"},{"version":"a8f820a380a2a06fc4fe1a54159067958f800929","status":"affected","lessThan":"75854cad5d80976f6ea0f0431f8cedd3bcc475cb","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/net/can/vxcan.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.12","versionType":"semver"},{"version":"4.14.218","status":"unaffected","lessThanOrEqual":"4.14.*","versionType":"semver"},{"version":"4.19.171","status":"unaffected","lessThanOrEqual":"4.19.*","versionType":"semver"},{"version":"5.4.93","status":"unaffected","lessThanOrEqual":"5.4.*","versionType":"semver"},{"version":"5.10.11","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.11","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/net/can/vxcan.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/6d6dcf2399cdd26f7f5426ca8dd8366b7f2ca105"},{"url":"https://git.kernel.org/stable/c/9b820875a32a3443d67bfd368e93038354e98052"},{"url":"https://git.kernel.org/stable/c/a24476b37167816e6352ca1a2cf3769847774f70"},{"url":"https://git.kernel.org/stable/c/e771a874076115df8bff27d325edfd2340e4ec69"},{"url":"https://git.kernel.org/stable/c/75854cad5d80976f6ea0f0431f8cedd3bcc475cb"}],"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 in vxcan_xmit, reached by sending a CAN frame on a virtual vxcan interface via PF_CAN/SOCK_RAW and RTNL setup—local syscalls/netlink only, not remote packet processing.\nAC:L - netif_rx_ni() runs softirq immediately and can_receive() always consume_skb()s the delivered frame, so the post-rx cfd->len access is a reliable use-after-free with no race or uncontrolled condition.\nPR:L - Creating/bringing up vxcan requires CAP_NET_ADMIN, which an unprivileged user obtains via user+network namespaces (unshare -Urn); sending on an existing up interface needs no capability.\nUI:N - The attacker creates the vxcan pair, brings it up, and sends frames entirely on their own—no victim interaction is required.\nS:U - Impact is confined to the local kernel (memory corruption / privilege escalation within the same security authority); this is not a VM/IOMMU/sandbox boundary escape.\nC:H - This is a use-after-free of skb data after delivery; a dangling read of freed heap enables disclosure of reclaimed object contents (including via stats that incorporate the stale byte).\nI:H - Use-after-free of the skb data buffer is exploitable via heap reuse/spray for corruption and control-flow hijacking primitives beyond the immediate stats update.\nA:H - Dereferencing freed skb data can oops/panic the kernel when the page is reclaimed or unmapped, and UAF faults are reliably triggerable on the success path."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T08:48:49.266Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.12","versionEndExcluding":"4.14.218"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.12","versionEndExcluding":"4.19.171"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.12","versionEndExcluding":"5.4.93"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.12","versionEndExcluding":"5.10.11"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.12","versionEndExcluding":"5.11"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"cvssV3_1":{"scope":"UNCHANGED","version":"3.1","baseScore":7.8,"attackVector":"LOCAL","baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","integrityImpact":"HIGH","userInteraction":"NONE","attackComplexity":"LOW","availabilityImpact":"HIGH","privilegesRequired":"LOW","confidentialityImpact":"HIGH"}},{"other":{"type":"ssvc","content":{"id":"CVE-2021-47669","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2025-04-17T18:17:52.149604Z"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-416","lang":"en","type":"CWE","description":"CWE-416 Use After Free"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2025-04-17T18:25:25.277Z"}}]}}}