{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2021-47520","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2024-05-24T15:02:54.824Z","datePublished":"2024-05-24T15:09:33.796Z","dateUpdated":"2026-08-05T08:48:14.519Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-05T08:48:14.519Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ncan: pch_can: pch_can_rx_normal: fix use after free\n\nAfter calling netif_receive_skb(skb), dereferencing skb is unsafe.\nEspecially, the can_frame cf which aliases skb memory is dereferenced\njust after the call netif_receive_skb(skb).\n\nReordering the lines solves the issue."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":8.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:A - The UAF is in the pch_can hardware RX path (PCI interrupt → NAPI → pch_can_rx_normal), triggered by Classical CAN frames arriving on the shared CAN bus; like Bluetooth/WiFi this is limited to the same physical bus segment, not Internet-routable.\nAC:L - Any received frame reliably hits the bug: can_receive() always consume_skb()s the original skb after delivery, so cf (aliasing skb data) is always dangling when cf->len is read; the attacker fully controls frame injection on the bus.\nPR:N - Exploitation requires only the ability to inject unauthenticated CAN frames onto the bus attached to the EG20T PCH controller; no local account or capability on the victim Linux system is needed.\nUI:N - No victim action is required beyond the CAN interface already being operational and receiving, which is the normal deployed state for this controller.\nS:U - Impact is confined to the local kernel's networking/stats path; there is no VM escape, IOMMU bypass, or other cross-authority boundary crossing.\nC:H - This is a use-after-free of skb/can_frame memory after netif_receive_skb; UAF of freed heap objects can be leveraged for information disclosure (including via the cf->len read into observable rx_bytes stats).\nI:H - Use-after-free of the skb backing store enables heap reuse/spray primitives that can be escalated to integrity compromise and control-flow hijacking under standard kernel UAF exploitation models.\nA:H - The deterministic UAF on every RX frame can cause kernel oops/panic (e.g. under KASAN or when the reclaimed page is unmapped), fully disrupting the system."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/net/can/pch_can.c"],"versions":[{"version":"b21d18b51b31a24d17f883b678432fbdee3d5675","lessThan":"bafe343a885c70dddf358379cf0b2a1c07355d8d","status":"affected","versionType":"git"},{"version":"b21d18b51b31a24d17f883b678432fbdee3d5675","lessThan":"3a3c46e2eff0577454860a203be1a8295f4acb76","status":"affected","versionType":"git"},{"version":"b21d18b51b31a24d17f883b678432fbdee3d5675","lessThan":"affbad02bf80380a7403885b9fe4a1587d1bb4f3","status":"affected","versionType":"git"},{"version":"b21d18b51b31a24d17f883b678432fbdee3d5675","lessThan":"3e193ef4e0a3f5bf92ede83ef214cb09d01b00aa","status":"affected","versionType":"git"},{"version":"b21d18b51b31a24d17f883b678432fbdee3d5675","lessThan":"abb4eff3dcd2e583060082a18a8dbf31f02689d4","status":"affected","versionType":"git"},{"version":"b21d18b51b31a24d17f883b678432fbdee3d5675","lessThan":"703dde112021c93d6e89443c070e7dbd4dea612e","status":"affected","versionType":"git"},{"version":"b21d18b51b31a24d17f883b678432fbdee3d5675","lessThan":"6c73fc931658d8cbc8a1714b326cb31eb71d16a7","status":"affected","versionType":"git"},{"version":"b21d18b51b31a24d17f883b678432fbdee3d5675","lessThan":"94cddf1e9227a171b27292509d59691819c458db","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/net/can/pch_can.c"],"versions":[{"version":"2.6.37","status":"affected"},{"version":"0","lessThan":"2.6.37","status":"unaffected","versionType":"semver"},{"version":"4.4.295","lessThanOrEqual":"4.4.*","status":"unaffected","versionType":"semver"},{"version":"4.9.293","lessThanOrEqual":"4.9.*","status":"unaffected","versionType":"semver"},{"version":"4.14.258","lessThanOrEqual":"4.14.*","status":"unaffected","versionType":"semver"},{"version":"4.19.221","lessThanOrEqual":"4.19.*","status":"unaffected","versionType":"semver"},{"version":"5.4.165","lessThanOrEqual":"5.4.*","status":"unaffected","versionType":"semver"},{"version":"5.10.85","lessThanOrEqual":"5.10.*","status":"unaffected","versionType":"semver"},{"version":"5.15.8","lessThanOrEqual":"5.15.*","status":"unaffected","versionType":"semver"},{"version":"5.16","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":"2.6.37","versionEndExcluding":"4.4.295"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.37","versionEndExcluding":"4.9.293"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.37","versionEndExcluding":"4.14.258"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.37","versionEndExcluding":"4.19.221"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.37","versionEndExcluding":"5.4.165"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.37","versionEndExcluding":"5.10.85"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.37","versionEndExcluding":"5.15.8"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.37","versionEndExcluding":"5.16"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/bafe343a885c70dddf358379cf0b2a1c07355d8d"},{"url":"https://git.kernel.org/stable/c/3a3c46e2eff0577454860a203be1a8295f4acb76"},{"url":"https://git.kernel.org/stable/c/affbad02bf80380a7403885b9fe4a1587d1bb4f3"},{"url":"https://git.kernel.org/stable/c/3e193ef4e0a3f5bf92ede83ef214cb09d01b00aa"},{"url":"https://git.kernel.org/stable/c/abb4eff3dcd2e583060082a18a8dbf31f02689d4"},{"url":"https://git.kernel.org/stable/c/703dde112021c93d6e89443c070e7dbd4dea612e"},{"url":"https://git.kernel.org/stable/c/6c73fc931658d8cbc8a1714b326cb31eb71d16a7"},{"url":"https://git.kernel.org/stable/c/94cddf1e9227a171b27292509d59691819c458db"}],"title":"can: 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