{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-98276", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-25T10:25:14.334Z", "datePublished": "2026-10-06T08:45:36.837Z", "dateUpdated": "2026-10-19T09:16:47.879Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T09:16:47.879Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: lock the socket in sock_gettstamp()\n\nsk->sk_flags must only be changed while holding the socket lock,\nbecause sock_set_flag() and sock_reset_flag() use non atomic\noperations (__set_bit() and __clear_bit()).\n\nsock_gettstamp() is one of the last places where a bit of sk->sk_flags\nis changed from a syscall without owning the socket lock, through\nsock_enable_timestamp(sk, SOCK_TIMESTAMP).\n\nsk_set_memalloc() and sk_clear_memalloc() also change sk->sk_flags\nwithout the socket lock, but their callers (nbd, iscsi_tcp, nvme-tcp,\nsunrpc, wireguard) need a careful audit, this will be addressed in a\nseparate patch.\n\nJungwoo Lee and Wongi Lee reported an UDP socket use-after-free\ncaused by this bug: a SIOCGSTAMPNS_NEW ioctl racing with bind()\ncan cancel the SOCK_RCU_FREE bit that udp_lib_get_port() just set,\nbecause both threads perform a read-modify-write on the same word.\n\n CPU 0 (bind) CPU 1 (SIOCGSTAMPNS_NEW)\n -------------------------------- ----------------------------\n read sk_flags = F read sk_flags = F\n compute F | BIT(SOCK_RCU_FREE) compute F | BIT(SOCK_TIMESTAMP)\n store F | BIT(SOCK_RCU_FREE)\n sk_add_node_rcu(sk, ...)\n store F | BIT(SOCK_TIMESTAMP)\n\nAfter the lost update, SOCK_RCU_FREE is clear while the socket is\nvisible to lockless UDP receive lookups. sk_destruct() then frees\nthe socket immediately instead of waiting for a RCU grace period,\nwhile the receive path still holds a reference-less pointer to it:\n\n BUG: KASAN: slab-use-after-free in ipv4_pktinfo_prepare+0x30/0x410\n Read of size 8 at addr ffff888008806610 by task exploit/207\n CPU: 0 UID: 1000 PID: 207 Comm: exploit Not tainted 6.12.95+ #1\n ipv4_pktinfo_prepare+0x30/0x410\n udp_queue_rcv_one_skb+0x51c/0x1180\n udp_unicast_rcv_skb+0x109/0x350\n ip_protocol_deliver_rcu+0x14b/0x310\n ip_local_deliver_finish+0x29d/0x390\n ip_local_deliver+0x24d/0x2a0\n\nOnly grab the socket lock when SOCK_TIMESTAMP has to be set,\nto keep the common case lockless." } ], "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 lost update is caused by a local process racing the SIOCGSTAMP*/SIOCGSTAMPNS* ioctl (sock_ioctl -> sock_gettstamp -> sock_enable_timestamp) against bind() -> udp_lib_get_port() setting SOCK_RCU_FREE on its own UDP socket. No network message supplies the triggering state; remote packets only deliver into the already-corrupted socket.\nAC:L - The attacker owns both sides of the race: one thread calls bind(), another calls the timestamp ioctl on the same fd. It can create, bind and close sockets in a loop until the __set_bit read-modify-write on sk_flags loses SOCK_RCU_FREE, then send loopback UDP to hit the freed sock.\nPR:L - It only needs an ordinary AF_INET/AF_INET6 UDP socket. sock_ioctl's SIOCGSTAMP case and inet bind to an ephemeral or unprivileged port have no capability check, and the reporters reproduced it as UID 1000.\nUI:N - The attacker drives every step (socket creation, concurrent bind/ioctl, close, sending packets to its own port) with no action from any other user.\nS:U - The freed struct sock and the code that reads it are both in the same kernel; this is local kernel memory corruption that leads to privilege escalation inside one authority, with no VM or sandbox boundary crossed.\nC:H - With SOCK_RCU_FREE lost, sk_destruct frees the UDP struct sock immediately while lockless RCU lookups in udp_unicast_rcv_skb/udp_queue_rcv_one_skb still hold a pointer to it. A slab UAF of a struct sock can be reclaimed with sprayed data to leak kernel memory.\nI:H - The receive path operates on the freed sock: it queues skbs, updates counters and reads sk_prot/sk_filter-related fields. If the attacker reclaims the slab, these become writes into, and function-pointer use from, attacker-controlled memory, which is a path to control-flow hijack.\nA:H - Even when not exploited, the use-after-free in ipv4_pktinfo_prepare/udp_queue_rcv_one_skb (shown by KASAN) corrupts slab memory and can oops or panic the kernel." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/core/sock.c" ], "versions": [ { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "18899e2e4023369a8f7739c2255a59a9748d8d17", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "88c804847dd87dc613b771b392ccecdb94725032", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "3b12d3967e96f1b7b977d9fc352ae29a1b299a82", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "17b2a1eb97fdb2a2cbaeab3b146b26797ea9311f", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "1f73253add8365d0dad0a4f421acaa8c21d20cef", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "d9f96bc2d822501f84d1caa6275a2c6b316ca2c4", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "899650bbf985b7bfd2a7b808357df9b16e6d6959", "status": "affected", "versionType": "git" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "9ed55f3dbef4f4adfe65eb03b0c35c53229a8490", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/core/sock.c" ], "versions": [ { "version": "2.6.12", "status": "affected" }, { "version": "0", "lessThan": "2.6.12", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.271", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.222", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.189", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.158", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.112", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.54", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.8", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "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": "2.6.12", "versionEndExcluding": "5.10.271" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "5.15.222" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "6.1.189" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "6.6.158" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "6.12.112" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "6.18.54" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "7.2.8" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.12", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/18899e2e4023369a8f7739c2255a59a9748d8d17" }, { "url": "https://git.kernel.org/stable/c/88c804847dd87dc613b771b392ccecdb94725032" }, { "url": "https://git.kernel.org/stable/c/3b12d3967e96f1b7b977d9fc352ae29a1b299a82" }, { "url": "https://git.kernel.org/stable/c/17b2a1eb97fdb2a2cbaeab3b146b26797ea9311f" }, { "url": "https://git.kernel.org/stable/c/1f73253add8365d0dad0a4f421acaa8c21d20cef" }, { "url": "https://git.kernel.org/stable/c/d9f96bc2d822501f84d1caa6275a2c6b316ca2c4" }, { "url": "https://git.kernel.org/stable/c/899650bbf985b7bfd2a7b808357df9b16e6d6959" }, { "url": "https://git.kernel.org/stable/c/9ed55f3dbef4f4adfe65eb03b0c35c53229a8490" } ], "title": "net: lock the socket in sock_gettstamp()", "x_generator": { "engine": "bippy-1.2.0" } } } }