--- id: CVE-2025-21959 title: >- In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conncount: Fully initialize struct nf_conncount_tuple in insert_tree() Since commit b36e4523d4d5 ("netfilter: nf_conncount: fix garbage collection confir… summary: >- In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conncount: Fully initialize struct nf_conncount_tuple in insert_tree() Since commit b36e4523d4d5 ("netfilter: nf_conncount: fix garbage collection confir… severity: medium cvss: 5.5 cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H' cwe: - CWE-908 vendor: linux product: linux_kernel affected: - 'linux_kernel >= 4.14.92, < 4.15' - 'linux_kernel >= 4.18, < 5.4.292' - 'linux_kernel >= 5.5, < 5.10.236' - 'linux_kernel >= 5.11, < 5.15.180' - 'linux_kernel >= 5.16, < 6.1.132' - 'linux_kernel >= 6.2, < 6.6.84' - 'linux_kernel >= 6.7, < 6.12.20' - 'linux_kernel >= 6.13, < 6.13.8' - linux_kernel = 6.14 patched: - linux_kernel 6.13.8 published: '2025-04-01' updated: '2026-07-14' source: NVD sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-21959' references: - url: 'https://git.kernel.org/stable/c/2a154ce766b995494e88d8d117fa82cc6b73dd87' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/2db5baaf047a7c8d6ed5e2cc657b7854e155b7fc' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/a62a25c6ad58fae997f48a0749afeda1c252ae51' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/d653bfeb07ebb3499c403404c21ac58a16531607' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/db1e0c0856821c59a32ea3af79476bf20a6beeb2' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/e8544a5a97bee3674e7cd6bf0f3a4af517fa9146' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/f522229c5563b59b4240261e406779bba6754159' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://git.kernel.org/stable/c/fda50302a13701d47fbe01e1739c7a51114144fb' label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 - url: 'https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://cert-portal.siemens.com/productcert/html/ssa-019113.html' label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e tags: - nvd - cve.org epss: 0.00431 epssPercentile: 0.34707 ingestedAt: '2026-07-14T13:36:56.128Z' ssvc: exploitation: none automatable: 'no' technicalImpact: partial timestamp: '2025-10-01T17:15:56.023953Z' --- ## Overview In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conncount: Fully initialize struct nf_conncount_tuple in insert_tree() Since commit b36e4523d4d5 ("netfilter: nf_conncount: fix garbage collection confirm race"), `cpu` and `jiffies32` were introduced to the struct nf_conncount_tuple. The commit made nf_conncount_add() initialize `conn->cpu` and `conn->jiffies32` when allocating the struct. In contrast, count_tree() was not changed to initialize them. By commit 34848d5c896e ("netfilter: nf_conncount: Split insert and traversal"), count_tree() was split and the relevant allocation code now resides in insert_tree(). Initialize `conn->cpu` and `conn->jiffies32` in insert_tree(). BUG: KMSAN: uninit-value in find_or_evict net/netfilter/nf_conncount.c:117 [inline] BUG: KMSAN: uninit-value in __nf_conncount_add+0xd9c/0x2850 net/netfilter/nf_conncount.c:143 find_or_evict net/netfilter/nf_conncount.c:117 [inline] __nf_conncount_add+0xd9c/0x2850 net/netfilter/nf_conncount.c:143 count_tree net/netfilter/nf_conncount.c:438 [inline] nf_conncount_count+0x82f/0x1e80 net/netfilter/nf_conncount.c:521 connlimit_mt+0x7f6/0xbd0 net/netfilter/xt_connlimit.c:72 __nft_match_eval net/netfilter/nft_compat.c:403 [inline] nft_match_eval+0x1a5/0x300 net/netfilter/nft_compat.c:433 expr_call_ops_eval net/netfilter/nf_tables_core.c:240 [inline] nft_do_chain+0x426/0x2290 net/netfilter/nf_tables_core.c:288 nft_do_chain_ipv4+0x1a5/0x230 net/netfilter/nft_chain_filter.c:23 nf_hook_entry_hookfn include/linux/netfilter.h:154 [inline] nf_hook_slow+0xf4/0x400 net/netfilter/core.c:626 nf_hook_slow_list+0x24d/0x860 net/netfilter/core.c:663 NF_HOOK_LIST include/linux/netfilter.h:350 [inline] ip_sublist_rcv+0x17b7/0x17f0 net/ipv4/ip_input.c:633 ip_list_rcv+0x9ef/0xa40 net/ipv4/ip_input.c:669 __netif_receive_skb_list_ptype net/core/dev.c:5936 [inline] __netif_receive_skb_list_core+0x15c5/0x1670 net/core/dev.c:5983 __netif_receive_skb_list net/core/dev.c:6035 [inline] netif_receive_skb_list_internal+0x1085/0x1700 net/core/dev.c:6126 netif_receive_skb_list+0x5a/0x460 net/core/dev.c:6178 xdp_recv_frames net/bpf/test_run.c:280 [inline] xdp_test_run_batch net/bpf/test_run.c:361 [inline] bpf_test_run_xdp_live+0x2e86/0x3480 net/bpf/test_run.c:390 bpf_prog_test_run_xdp+0xf1d/0x1ae0 net/bpf/test_run.c:1316 bpf_prog_test_run+0x5e5/0xa30 kernel/bpf/syscall.c:4407 __sys_bpf+0x6aa/0xd90 kernel/bpf/syscall.c:5813 __do_sys_bpf kernel/bpf/syscall.c:5902 [inline] __se_sys_bpf kernel/bpf/syscall.c:5900 [inline] __ia32_sys_bpf+0xa0/0xe0 kernel/bpf/syscall.c:5900 ia32_sys_call+0x394d/0x4180 arch/x86/include/generated/asm/syscalls_32.h:358 do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline] __do_fast_syscall_32+0xb0/0x110 arch/x86/entry/common.c:387 do_fast_syscall_32+0x38/0x80 arch/x86/entry/common.c:412 do_SYSENTER_32+0x1f/0x30 arch/x86/entry/common.c:450 entry_SYSENTER_compat_after_hwframe+0x84/0x8e Uninit was created at: slab_post_alloc_hook mm/slub.c:4121 [inline] slab_alloc_node mm/slub.c:4164 [inline] kmem_cache_alloc_noprof+0x915/0xe10 mm/slub.c:4171 insert_tree net/netfilter/nf_conncount.c:372 [inline] count_tree net/netfilter/nf_conncount.c:450 [inline] nf_conncount_count+0x1415/0x1e80 net/netfilter/nf_conncount.c:521 connlimit_mt+0x7f6/0xbd0 net/netfilter/xt_connlimit.c:72 __nft_match_eval net/netfilter/nft_compat.c:403 [inline] nft_match_eval+0x1a5/0x300 net/netfilter/nft_compat.c:433 expr_call_ops_eval net/netfilter/nf_tables_core.c:240 [inline] nft_do_chain+0x426/0x2290 net/netfilter/nf_tables_core.c:288 nft_do_chain_ipv4+0x1a5/0x230 net/netfilter/nft_chain_filter.c:23 nf_hook_entry_hookfn include/linux/netfilter.h:154 [inline] nf_hook_slow+0xf4/0x400 net/netfilter/core.c:626 nf_hook_slow_list+0x24d/0x860 net/netfilter/core.c:663 NF_HOOK_LIST include/linux/netfilter.h:350 [inline] ip_sublist_rcv+0x17b7/0x17f0 net/ipv4/ip_input.c:633 ip_list_rcv+0x9ef/0xa40 net/ip ---truncated--- ## Affected - `linux_kernel >= 4.14.92, < 4.15` - `linux_kernel >= 4.18, < 5.4.292` - `linux_kernel >= 5.5, < 5.10.236` - `linux_kernel >= 5.11, < 5.15.180` - `linux_kernel >= 5.16, < 6.1.132` - `linux_kernel >= 6.2, < 6.6.84` - `linux_kernel >= 6.7, < 6.12.20` - `linux_kernel >= 6.13, < 6.13.8` - `linux_kernel = 6.14` ## Remediation Upgrade past the affected range: - `linux_kernel 6.13.8`