{"id":"CVE-2026-74666","state":"PUBLISHED","title":"packet: synchronize pressure clearing with ring reconfiguration","description":"In the Linux kernel, the following vulnerability has been resolved:\n\npacket: synchronize pressure clearing with ring reconfiguration\n\npacket_set_ring() updates the RX ring state under sk_receive_queue.lock,\nbut used to publish the tpacket receive mode through po->prot_hook.func\nafter releasing that lock. packet_poll() and packet_recvmsg() can then\nrun the pressure clearing path after the ring has been cleared while\nstill seeing tpacket_rcv, causing __packet_rcv_has_room() to dereference\nstale or NULL ring storage.\n\nMove the existing receive hook assignment into the same\nsk_receive_queue.lock section as the ring state update. Keep the\nassignment otherwise unchanged, including on TX ring reconfiguration, to\navoid adding behavior changes that are not required for the fix.\n\nSerialize packet_recvmsg() pressure clearing with the same queue lock\nonly after PACKET_SOCK_PRESSURE has been observed. If the flag is clear\nand the socket has moved away from tpacket_rcv, packet_set_ring() has\nalready detached the socket and waited for synchronize_net(), so no new\npacket input can set the flag again.\n\npacket_poll() already holds sk_receive_queue.lock, so it uses the new\nunlocked helper directly.","publishedAt":"2026-08-22T15:32:38.098Z","updatedAt":"2026-10-16T19:16:08.102Z","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":"2ccdbaa6d55b0656244ba57c4b56765a0af76c0a","status":"affected","lessThan":"bf3c8e86bc8ad111be3f3136125e255344bcb3da","versionType":"git"},{"version":"2ccdbaa6d55b0656244ba57c4b56765a0af76c0a","status":"affected","lessThan":"8cfb2e71926a682f36c4240067d424074dd8f70f","versionType":"git"},{"version":"2ccdbaa6d55b0656244ba57c4b56765a0af76c0a","status":"affected","lessThan":"f015c9de92b731814059a343b765c60c0196225c","versionType":"git"},{"version":"2ccdbaa6d55b0656244ba57c4b56765a0af76c0a","status":"affected","lessThan":"cf8189b82bb93f219ab740e0346c919ad65ada62","versionType":"git"},{"version":"2ccdbaa6d55b0656244ba57c4b56765a0af76c0a","status":"affected","lessThan":"ad740b4990347521f0db260d381f9f74e7b340ba","versionType":"git"},{"version":"2ccdbaa6d55b0656244ba57c4b56765a0af76c0a","status":"affected","lessThan":"2c7b5eb87b2b288cdbde825f21d2b83b2f5da747","versionType":"git"},{"version":"2ccdbaa6d55b0656244ba57c4b56765a0af76c0a","status":"affected","lessThan":"a08196c3cc105947746ec21309edfbb60275fcdb","versionType":"git"},{"version":"2ccdbaa6d55b0656244ba57c4b56765a0af76c0a","status":"affected","lessThan":"1a35da325cac4d5bcad76a2aa943408a6f1d9000","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/packet/af_packet.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.2","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.2","versionType":"semver"},{"version":"5.10.267","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.218","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.185","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.152","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.104","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.45","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.9","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/packet/af_packet.c"]}],"references":["https://git.kernel.org/stable/c/bf3c8e86bc8ad111be3f3136125e255344bcb3da","https://git.kernel.org/stable/c/8cfb2e71926a682f36c4240067d424074dd8f70f","https://git.kernel.org/stable/c/f015c9de92b731814059a343b765c60c0196225c","https://git.kernel.org/stable/c/cf8189b82bb93f219ab740e0346c919ad65ada62","https://git.kernel.org/stable/c/ad740b4990347521f0db260d381f9f74e7b340ba","https://git.kernel.org/stable/c/2c7b5eb87b2b288cdbde825f21d2b83b2f5da747","https://git.kernel.org/stable/c/a08196c3cc105947746ec21309edfbb60275fcdb","https://git.kernel.org/stable/c/1a35da325cac4d5bcad76a2aa943408a6f1d9000"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:58.252Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/74xxx/CVE-2026-74666.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-74666","state":"PUBLISHED","datePublished":"2026-08-22T15:32:38.098Z","dateUpdated":"2026-10-16T19:16:08.102Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-08-15T05:44:03.924Z"},"containers":{"cna":{"title":"packet: synchronize pressure clearing with ring reconfiguration","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\npacket: synchronize pressure clearing with ring reconfiguration\n\npacket_set_ring() updates the RX ring state under sk_receive_queue.lock,\nbut used to publish the tpacket receive mode through po->prot_hook.func\nafter releasing that lock. packet_poll() and packet_recvmsg() can then\nrun the pressure clearing path after the ring has been cleared while\nstill seeing tpacket_rcv, causing __packet_rcv_has_room() to dereference\nstale or NULL ring storage.\n\nMove the existing receive hook assignment into the same\nsk_receive_queue.lock section as the ring state update. Keep the\nassignment otherwise unchanged, including on TX ring reconfiguration, to\navoid adding behavior changes that are not required for the fix.\n\nSerialize packet_recvmsg() pressure clearing with the same queue lock\nonly after PACKET_SOCK_PRESSURE has been observed. If the flag is clear\nand the socket has moved away from tpacket_rcv, packet_set_ring() has\nalready detached the socket and waited for synchronize_net(), so no new\npacket input can set the flag again.\n\npacket_poll() already holds sk_receive_queue.lock, so it uses the new\nunlocked helper directly."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"2ccdbaa6d55b0656244ba57c4b56765a0af76c0a","status":"affected","lessThan":"bf3c8e86bc8ad111be3f3136125e255344bcb3da","versionType":"git"},{"version":"2ccdbaa6d55b0656244ba57c4b56765a0af76c0a","status":"affected","lessThan":"8cfb2e71926a682f36c4240067d424074dd8f70f","versionType":"git"},{"version":"2ccdbaa6d55b0656244ba57c4b56765a0af76c0a","status":"affected","lessThan":"f015c9de92b731814059a343b765c60c0196225c","versionType":"git"},{"version":"2ccdbaa6d55b0656244ba57c4b56765a0af76c0a","status":"affected","lessThan":"cf8189b82bb93f219ab740e0346c919ad65ada62","versionType":"git"},{"version":"2ccdbaa6d55b0656244ba57c4b56765a0af76c0a","status":"affected","lessThan":"ad740b4990347521f0db260d381f9f74e7b340ba","versionType":"git"},{"version":"2ccdbaa6d55b0656244ba57c4b56765a0af76c0a","status":"affected","lessThan":"2c7b5eb87b2b288cdbde825f21d2b83b2f5da747","versionType":"git"},{"version":"2ccdbaa6d55b0656244ba57c4b56765a0af76c0a","status":"affected","lessThan":"a08196c3cc105947746ec21309edfbb60275fcdb","versionType":"git"},{"version":"2ccdbaa6d55b0656244ba57c4b56765a0af76c0a","status":"affected","lessThan":"1a35da325cac4d5bcad76a2aa943408a6f1d9000","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/packet/af_packet.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.2","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.2","versionType":"semver"},{"version":"5.10.267","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.218","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.185","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.152","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.104","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.45","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.9","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/packet/af_packet.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/bf3c8e86bc8ad111be3f3136125e255344bcb3da"},{"url":"https://git.kernel.org/stable/c/8cfb2e71926a682f36c4240067d424074dd8f70f"},{"url":"https://git.kernel.org/stable/c/f015c9de92b731814059a343b765c60c0196225c"},{"url":"https://git.kernel.org/stable/c/cf8189b82bb93f219ab740e0346c919ad65ada62"},{"url":"https://git.kernel.org/stable/c/ad740b4990347521f0db260d381f9f74e7b340ba"},{"url":"https://git.kernel.org/stable/c/2c7b5eb87b2b288cdbde825f21d2b83b2f5da747"},{"url":"https://git.kernel.org/stable/c/a08196c3cc105947746ec21309edfbb60275fcdb"},{"url":"https://git.kernel.org/stable/c/1a35da325cac4d5bcad76a2aa943408a6f1d9000"}],"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 hit only from local AF_PACKET syscalls—setsockopt(PACKET_RX_RING) racing poll(2)/recvmsg(2) pressure clearing in packet_poll()/packet_recvmsg()—not from remote packet receive paths like ksmbd, nfsd, or the TCP/IP stack.\nAC:L - The attacker controls both race sides: one thread polls/recvmsg while PACKET_SOCK_PRESSURE is set, another tears down the RX ring via PACKET_RX_RING; packet_set_ring()'s synchronize_net() window makes the stale tpacket_rcv vs NULL/freed pg_vec mismatch reliably winnable.\nPR:L - packet_create() requires ns_capable(net->user_ns, CAP_NET_RAW); unprivileged users obtain CAP_NET_RAW via user+network namespaces (unshare -Urn) or container defaults (Docker NET_RAW), without init-namespace root.\nUI:N - No victim action is required; the attacker creates the AF_PACKET socket, configures the mmap RX ring, fills it to set PACKET_SOCK_PRESSURE, and races ring teardown against its own poll/recvmsg calls.\nS:U - Stale/NULL ring dereferences corrupt kernel heap state on the same host; this is standard kernel memory corruption within one security authority, not a VM escape, IOMMU bypass, or other cross-boundary scope change.\nC:H - __packet_rcv_has_room() follows tpacket_rcv and dereferences rb->pg_vec or prb_bdqc block pointers after packet_set_ring() cleared/freed the ring, yielding NULL-dereference or use-after-free reads of ring metadata and mmap-backed pages.\nI:H - Freed ring storage and stale prb_bdqc/pkbdq pointers remain attacker-influenced through mmap and concurrent ring operations, providing a controllable kernel heap use-after-free write primitive typical of AF_PACKET ring reconfiguration races.\nA:H - NULL pg_vec indexing in packet_lookup_frame() or stale block access in prb_lookup_block() from the pressure-clearing path causes an immediate kernel oops/panic, giving any qualifying local attacker repeatable host-wide denial of service."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-27T12:40:00.544Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.2","versionEndExcluding":"5.10.267"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.2","versionEndExcluding":"5.15.218"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.2","versionEndExcluding":"6.1.185"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.2","versionEndExcluding":"6.6.152"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.2","versionEndExcluding":"6.12.104"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.2","versionEndExcluding":"6.18.45"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.2","versionEndExcluding":"7.1.9"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.2","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-74666","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T19:14:12.266180Z"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-16T19:16:08.102Z"}}]}}}