{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-31665", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-03-09T15:48:24.129Z", "datePublished": "2026-04-24T14:45:14.613Z", "dateUpdated": "2026-08-05T12:24:15.035Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:24:15.035Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nft_ct: fix use-after-free in timeout object destroy\n\nnft_ct_timeout_obj_destroy() frees the timeout object with kfree()\nimmediately after nf_ct_untimeout(), without waiting for an RCU grace\nperiod. Concurrent packet processing on other CPUs may still hold\nRCU-protected references to the timeout object obtained via\nrcu_dereference() in nf_ct_timeout_data().\n\nAdd an rcu_head to struct nf_ct_timeout and use kfree_rcu() to defer\nfreeing until after an RCU grace period, matching the approach already\nused in nfnetlink_cttimeout.c.\n\nKASAN report:\n BUG: KASAN: slab-use-after-free in nf_conntrack_tcp_packet+0x1381/0x29d0\n Read of size 4 at addr ffff8881035fe19c by task exploit/80\n\n Call Trace:\n nf_conntrack_tcp_packet+0x1381/0x29d0\n nf_conntrack_in+0x612/0x8b0\n nf_hook_slow+0x70/0x100\n __ip_local_out+0x1b2/0x210\n tcp_sendmsg_locked+0x722/0x1580\n __sys_sendto+0x2d8/0x320\n\n Allocated by task 75:\n nft_ct_timeout_obj_init+0xf6/0x290\n nft_obj_init+0x107/0x1b0\n nf_tables_newobj+0x680/0x9c0\n nfnetlink_rcv_batch+0xc29/0xe00\n\n Freed by task 26:\n nft_obj_destroy+0x3f/0xa0\n nf_tables_trans_destroy_work+0x51c/0x5c0\n process_one_work+0x2c4/0x5a0" } ], "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 vulnerable timeout object is created and destroyed through nftables netlink operations, and the stale pointer is exercised by local packet/syscall activity such as sendto through conntrack. Netfilter/nftables control-plane access is a local attack surface, not a remotely unauthenticated one.\nAC:L - The attacker can create the timeout object, attach it to conntrack state, delete it, and generate concurrent packet processing themselves. The UAF race is between attacker-controlled netlink teardown and attacker-controlled traffic, with no external condition required.\nPR:L - nfnetlink requires CAP_NET_ADMIN, but this is checked against the network namespace user_ns, so an unprivileged user can reach it via user and network namespaces on common configurations. This is therefore low privileges rather than real init-namespace root.\nUI:N - No victim interaction is required once the attacker has local execution. The attacker can perform the nftables operations and packet generation directly.\nS:U - The vulnerability is in the kernel netfilter/conntrack subsystem and impacts the same kernel security authority. It does not cross a VM, hypervisor, or separate authorization boundary.\nC:H - This is a use-after-free of an RCU-protected conntrack timeout object during packet processing. A kernel UAF can be shaped through heap reuse and is defensibly treated as enabling high confidentiality impact.\nI:H - Use-after-free in kernel heap memory can be leveraged through heap spraying and object replacement toward memory corruption or control-flow manipulation. Under the required overestimation rule, integrity impact is high.\nA:H - The fix commit includes a KASAN slab-use-after-free report in nf_conntrack_tcp_packet, and such UAFs can crash or destabilize the kernel. Repeated local triggering makes high availability impact appropriate." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "include/net/netfilter/nf_conntrack_timeout.h", "net/netfilter/nft_ct.c" ], "versions": [ { "version": "7e0b2b57f01d183e1c84114f1f2287737358d748", "lessThan": "c458fc1c278a65ad5381083121d39a479973ebed", "status": "affected", "versionType": "git" }, { "version": "7e0b2b57f01d183e1c84114f1f2287737358d748", "lessThan": "c581e5c8f2b59158f62efe61c1a3dc36189081ff", "status": "affected", "versionType": "git" }, { "version": "7e0b2b57f01d183e1c84114f1f2287737358d748", "lessThan": "f16fe84879a5280f05ebbcea593a189ba0f3e79a", "status": "affected", "versionType": "git" }, { "version": "7e0b2b57f01d183e1c84114f1f2287737358d748", "lessThan": "070abdf1b04325b21a20a2a0c39a2208af107275", "status": "affected", "versionType": "git" }, { "version": "7e0b2b57f01d183e1c84114f1f2287737358d748", "lessThan": "aa7cfa16f98f8ec3e6d47c34e1a8c1ae4b9b8b77", "status": "affected", "versionType": "git" }, { "version": "7e0b2b57f01d183e1c84114f1f2287737358d748", "lessThan": "b42aca3660dc2627a29a38131597ca610dc451f9", "status": "affected", "versionType": "git" }, { "version": "7e0b2b57f01d183e1c84114f1f2287737358d748", "lessThan": "d0983b48c10d1509fd795c155f8b1e832e1369ff", "status": "affected", "versionType": "git" }, { "version": "7e0b2b57f01d183e1c84114f1f2287737358d748", "lessThan": "f8dca15a1b190787bbd03285304b569631160eda", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "include/net/netfilter/nf_conntrack_timeout.h", "net/netfilter/nft_ct.c" ], "versions": [ { "version": "4.19", "status": "affected" }, { "version": "0", "lessThan": "4.19", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.253", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.203", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.169", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.135", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.82", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.23", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.19.13", "lessThanOrEqual": "6.19.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0", "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": "4.19", "versionEndExcluding": "5.10.253" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.19", "versionEndExcluding": "5.15.203" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.19", "versionEndExcluding": "6.1.169" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.19", "versionEndExcluding": "6.6.135" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.19", "versionEndExcluding": "6.12.82" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.19", "versionEndExcluding": "6.18.23" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.19", "versionEndExcluding": "6.19.13" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.19", "versionEndExcluding": "7.0" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/c458fc1c278a65ad5381083121d39a479973ebed" }, { "url": "https://git.kernel.org/stable/c/c581e5c8f2b59158f62efe61c1a3dc36189081ff" }, { "url": "https://git.kernel.org/stable/c/f16fe84879a5280f05ebbcea593a189ba0f3e79a" }, { "url": "https://git.kernel.org/stable/c/070abdf1b04325b21a20a2a0c39a2208af107275" }, { "url": "https://git.kernel.org/stable/c/aa7cfa16f98f8ec3e6d47c34e1a8c1ae4b9b8b77" }, { "url": "https://git.kernel.org/stable/c/b42aca3660dc2627a29a38131597ca610dc451f9" }, { "url": "https://git.kernel.org/stable/c/d0983b48c10d1509fd795c155f8b1e832e1369ff" }, { "url": "https://git.kernel.org/stable/c/f8dca15a1b190787bbd03285304b569631160eda" } ], "title": "netfilter: nft_ct: fix use-after-free in timeout object destroy", "x_generator": { 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