{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-21959", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-12-29T08:45:45.793Z", "datePublished": "2025-04-01T15:46:57.775Z", "dateUpdated": "2026-08-05T11:55:37.933Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:55:37.933Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_conncount: Fully initialize struct nf_conncount_tuple in insert_tree()\n\nSince commit b36e4523d4d5 (\"netfilter: nf_conncount: fix garbage\ncollection confirm race\"), `cpu` and `jiffies32` were introduced to\nthe struct nf_conncount_tuple.\n\nThe commit made nf_conncount_add() initialize `conn->cpu` and\n`conn->jiffies32` when allocating the struct.\nIn contrast, count_tree() was not changed to initialize them.\n\nBy commit 34848d5c896e (\"netfilter: nf_conncount: Split insert and\ntraversal\"), count_tree() was split and the relevant allocation\ncode now resides in insert_tree().\nInitialize `conn->cpu` and `conn->jiffies32` in insert_tree().\n\nBUG: KMSAN: uninit-value in find_or_evict net/netfilter/nf_conncount.c:117 [inline]\nBUG: KMSAN: uninit-value in __nf_conncount_add+0xd9c/0x2850 net/netfilter/nf_conncount.c:143\n find_or_evict net/netfilter/nf_conncount.c:117 [inline]\n __nf_conncount_add+0xd9c/0x2850 net/netfilter/nf_conncount.c:143\n count_tree net/netfilter/nf_conncount.c:438 [inline]\n nf_conncount_count+0x82f/0x1e80 net/netfilter/nf_conncount.c:521\n connlimit_mt+0x7f6/0xbd0 net/netfilter/xt_connlimit.c:72\n __nft_match_eval net/netfilter/nft_compat.c:403 [inline]\n nft_match_eval+0x1a5/0x300 net/netfilter/nft_compat.c:433\n expr_call_ops_eval net/netfilter/nf_tables_core.c:240 [inline]\n nft_do_chain+0x426/0x2290 net/netfilter/nf_tables_core.c:288\n nft_do_chain_ipv4+0x1a5/0x230 net/netfilter/nft_chain_filter.c:23\n nf_hook_entry_hookfn include/linux/netfilter.h:154 [inline]\n nf_hook_slow+0xf4/0x400 net/netfilter/core.c:626\n nf_hook_slow_list+0x24d/0x860 net/netfilter/core.c:663\n NF_HOOK_LIST include/linux/netfilter.h:350 [inline]\n ip_sublist_rcv+0x17b7/0x17f0 net/ipv4/ip_input.c:633\n ip_list_rcv+0x9ef/0xa40 net/ipv4/ip_input.c:669\n __netif_receive_skb_list_ptype net/core/dev.c:5936 [inline]\n __netif_receive_skb_list_core+0x15c5/0x1670 net/core/dev.c:5983\n __netif_receive_skb_list net/core/dev.c:6035 [inline]\n netif_receive_skb_list_internal+0x1085/0x1700 net/core/dev.c:6126\n netif_receive_skb_list+0x5a/0x460 net/core/dev.c:6178\n xdp_recv_frames net/bpf/test_run.c:280 [inline]\n xdp_test_run_batch net/bpf/test_run.c:361 [inline]\n bpf_test_run_xdp_live+0x2e86/0x3480 net/bpf/test_run.c:390\n bpf_prog_test_run_xdp+0xf1d/0x1ae0 net/bpf/test_run.c:1316\n bpf_prog_test_run+0x5e5/0xa30 kernel/bpf/syscall.c:4407\n __sys_bpf+0x6aa/0xd90 kernel/bpf/syscall.c:5813\n __do_sys_bpf kernel/bpf/syscall.c:5902 [inline]\n __se_sys_bpf kernel/bpf/syscall.c:5900 [inline]\n __ia32_sys_bpf+0xa0/0xe0 kernel/bpf/syscall.c:5900\n ia32_sys_call+0x394d/0x4180 arch/x86/include/generated/asm/syscalls_32.h:358\n do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]\n __do_fast_syscall_32+0xb0/0x110 arch/x86/entry/common.c:387\n do_fast_syscall_32+0x38/0x80 arch/x86/entry/common.c:412\n do_SYSENTER_32+0x1f/0x30 arch/x86/entry/common.c:450\n entry_SYSENTER_compat_after_hwframe+0x84/0x8e\n\nUninit was created at:\n slab_post_alloc_hook mm/slub.c:4121 [inline]\n slab_alloc_node mm/slub.c:4164 [inline]\n kmem_cache_alloc_noprof+0x915/0xe10 mm/slub.c:4171\n insert_tree net/netfilter/nf_conncount.c:372 [inline]\n count_tree net/netfilter/nf_conncount.c:450 [inline]\n nf_conncount_count+0x1415/0x1e80 net/netfilter/nf_conncount.c:521\n connlimit_mt+0x7f6/0xbd0 net/netfilter/xt_connlimit.c:72\n __nft_match_eval net/netfilter/nft_compat.c:403 [inline]\n nft_match_eval+0x1a5/0x300 net/netfilter/nft_compat.c:433\n expr_call_ops_eval net/netfilter/nf_tables_core.c:240 [inline]\n nft_do_chain+0x426/0x2290 net/netfilter/nf_tables_core.c:288\n nft_do_chain_ipv4+0x1a5/0x230 net/netfilter/nft_chain_filter.c:23\n nf_hook_entry_hookfn include/linux/netfilter.h:154 [inline]\n nf_hook_slow+0xf4/0x400 net/netfilter/core.c:626\n nf_hook_slow_list+0x24d/0x860 net/netfilter/core.c:663\n NF_HOOK_LIST include/linux/netfilter.h:350 [inline]\n ip_sublist_rcv+0x17b7/0x17f0 net/ipv4/ip_input.c:633\n ip_list_rcv+0x9ef/0xa40 net/ip\n---truncated---" } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L", "baseScore": 7.3, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:N - The vulnerable `insert_tree()` allocation and the subsequent `find_or_evict()` read of the uninitialized fields execute in the netfilter packet-receive path (`ip_list_rcv → nf_hook_slow → connlimit_mt`/`ovs_ct_check_limit`) on packets arriving from remote peers. A remote host simply sending connections to a box carrying an iptables `-m connlimit` rule or an OVS conntrack zone limit drives the code.\nAC:L - The fields are left uninitialized on every `insert_tree()` allocation, and the attacker controls both sides of the conditioning window by opening many concurrent connections from the same source prefix so entries remain unconfirmed when `find_or_evict()` walks them. `CONFIG_NETFILTER_XT_MATCH_CONNLIMIT` is shipped by all mainstream distributions and connlimit/OVS ct-limit rules are common on internet-facing and cloud deployments, so no rare configuration is required.\nPR:N - The path is reached from raw inbound IP packets processed in a netfilter hook before any authentication or authorization; no account, credential, or capability on the target is needed. The alternative local trigger via unprivileged user namespaces would only be PR:L, so the unauthenticated remote scenario dominates.\nUI:N - Exploitation requires only that the attacker transmit packets to the target; no administrator or user action is needed once the connlimit/ct-limit rule is in place.\nS:U - The uninitialized read and its consequences are confined to the kernel's own nf_conncount accounting state within the same security authority; no VM, IOMMU, container, or sandbox boundary is crossed.\nC:L - `conn->cpu` and `conn->jiffies32` are read from recycled slab memory (the cache is created with flags 0, so it is merge-eligible with other same-size caches) and the values steer whether a packet is accepted or dropped, giving a remote observer a limited, bounded inference channel into residual kernel heap contents. Nothing is copied out directly, so the disclosure is limited rather than arbitrary read.\nI:L - The garbage values corrupt nf_conncount's eviction heuristic so `list->count` no longer reflects the real number of tracked connections, causing the administrator-configured connlimit / OVS per-zone limit to be enforced against a wrong count and letting an attacker exceed it. This is a limited modification of security-relevant kernel state, not an arbitrary write or control-flow hijack.\nA:L - Under-counting defeats a connection-limit control that exists to prevent resource exhaustion, letting an attacker consume more connections than permitted, while transient over-counting drops legitimate traffic from an affected source. The fields are only compared, never dereferenced or used as indices, so there is no oops, panic, hang, or memory corruption — the result is degradation rather than total loss of availability." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/netfilter/nf_conncount.c" ], "versions": [ { "version": "b36e4523d4d56e2595e28f16f6ccf1cd6a9fc452", "lessThan": "f522229c5563b59b4240261e406779bba6754159", "status": "affected", "versionType": "git" }, { "version": "b36e4523d4d56e2595e28f16f6ccf1cd6a9fc452", "lessThan": "2a154ce766b995494e88d8d117fa82cc6b73dd87", "status": "affected", "versionType": "git" }, { "version": "b36e4523d4d56e2595e28f16f6ccf1cd6a9fc452", "lessThan": "e8544a5a97bee3674e7cd6bf0f3a4af517fa9146", "status": "affected", "versionType": "git" }, { "version": "b36e4523d4d56e2595e28f16f6ccf1cd6a9fc452", "lessThan": "a62a25c6ad58fae997f48a0749afeda1c252ae51", "status": "affected", "versionType": "git" }, { "version": "b36e4523d4d56e2595e28f16f6ccf1cd6a9fc452", "lessThan": "fda50302a13701d47fbe01e1739c7a51114144fb", "status": "affected", "versionType": "git" }, { "version": "b36e4523d4d56e2595e28f16f6ccf1cd6a9fc452", "lessThan": "db1e0c0856821c59a32ea3af79476bf20a6beeb2", "status": "affected", "versionType": "git" }, { "version": "b36e4523d4d56e2595e28f16f6ccf1cd6a9fc452", "lessThan": "2db5baaf047a7c8d6ed5e2cc657b7854e155b7fc", "status": "affected", "versionType": "git" }, { "version": "b36e4523d4d56e2595e28f16f6ccf1cd6a9fc452", "lessThan": "d653bfeb07ebb3499c403404c21ac58a16531607", "status": "affected", "versionType": "git" }, { "version": "75af3d78168e654a5cd8bbc4c774f97be836165f", "status": "affected", "versionType": "git" }, { "version": "4.14.92", "lessThan": "4.15", "status": "affected", "versionType": "semver" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/netfilter/nf_conncount.c" ], "versions": [ { "version": "4.18", "status": "affected" }, { "version": "0", "lessThan": "4.18", "status": "unaffected", "versionType": "semver" }, { "version": "5.4.292", "lessThanOrEqual": "5.4.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.236", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.180", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.132", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.84", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.20", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.13.8", "lessThanOrEqual": "6.13.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.14", "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": "4.18", "versionEndExcluding": "5.4.292" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.18", "versionEndExcluding": "5.10.236" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.18", "versionEndExcluding": "5.15.180" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.18", "versionEndExcluding": "6.1.132" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.18", "versionEndExcluding": "6.6.84" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.18", "versionEndExcluding": "6.12.20" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.18", "versionEndExcluding": "6.13.8" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.18", "versionEndExcluding": "6.14" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.14.92" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/f522229c5563b59b4240261e406779bba6754159" }, { "url": "https://git.kernel.org/stable/c/2a154ce766b995494e88d8d117fa82cc6b73dd87" }, { "url": "https://git.kernel.org/stable/c/e8544a5a97bee3674e7cd6bf0f3a4af517fa9146" }, { "url": "https://git.kernel.org/stable/c/a62a25c6ad58fae997f48a0749afeda1c252ae51" }, { "url": "https://git.kernel.org/stable/c/fda50302a13701d47fbe01e1739c7a51114144fb" }, { "url": "https://git.kernel.org/stable/c/db1e0c0856821c59a32ea3af79476bf20a6beeb2" }, { "url": "https://git.kernel.org/stable/c/2db5baaf047a7c8d6ed5e2cc657b7854e155b7fc" }, { "url": "https://git.kernel.org/stable/c/d653bfeb07ebb3499c403404c21ac58a16531607" } ], "title": "netfilter: nf_conncount: Fully initialize struct nf_conncount_tuple in insert_tree()", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "problemTypes": [ { "descriptions": [ { "type": "CWE", "cweId": "CWE-908", "lang": "en", "description": "CWE-908 Use of Uninitialized Resource" } ] } ], "metrics": [ { "cvssV3_1": { "scope": "UNCHANGED", "version": "3.1", "baseScore": 5.5, "attackVector": "LOCAL", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "LOW", "confidentialityImpact": "NONE" } }, { "other": { "type": "ssvc", "content": { "timestamp": "2025-10-01T17:15:56.023953Z", "id": "CVE-2025-21959", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "partial" } ], "role": "CISA Coordinator", "version": "2.0.3" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2025-10-01T17:15:58.938Z" } }, { "title": "CVE Program Container", "references": [ { "url": "https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html" }, { "url": "https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html" } ], "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2025-11-03T19:40:01.234Z" } }, { "x_adpType": "supplier", "providerMetadata": { "orgId": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e", "shortName": "siemens-SADP", "dateUpdated": "2026-07-14T12:40:35.517Z" }, "affected": [ { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.6", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" }, { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.6", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" }, { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.6", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" }, { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.6", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" }, { "vendor": "Siemens", "product": "SIPLUS S7-1500 CPU 1518-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.6", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" } ], "references": [ { "url": "https://cert-portal.siemens.com/productcert/html/ssa-019113.html" } ] } ] } }