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CVE-2026-72251— netfilter: nf_nat_sip: reload possible stale data pointer

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会开源的一个操作系统内核。 Linux kernel存在安全漏洞，该漏洞源于nf_nat_sip函数中skb_ensure_writable重新分配后未更新数据指针，可能导致内存错误和头部损坏。

CVSS 9.8 · Critical EPSS 0.70% · P50

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux 7266507d89991fa1e989283e4e032c6d9357fe26< bded21a4bf9bf86a79148be735723a97ca9a7532 affected
7266507d89991fa1e989283e4e032c6d9357fe26< dc11f26685aa850f237226f0f463647aea58ab7c affected
7266507d89991fa1e989283e4e032c6d9357fe26< e38143c9b477f2968024c47c647dd4456a40aff1 affected
7266507d89991fa1e989283e4e032c6d9357fe26< 57e4e29644ec054d7021d296407e7ddd844afea2 affected
7266507d89991fa1e989283e4e032c6d9357fe26< eae9c6ccb5af69c713a65f8ae219f5c1aa32cd17 affected
7266507d89991fa1e989283e4e032c6d9357fe26< 2bcf2c5052fb5e73e255140ab43f056aef409c27 affected
7266507d89991fa1e989283e4e032c6d9357fe26< 0e76e3e886cc9ee027337d5ad39cb96f57b7bdc7 affected
7266507d89991fa1e989283e4e032c6d9357fe26< 77e43bcb7ec177e293a5c3f1b91a2c5aebfb6c68 affected
… +10 more rows
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I. Basic Information for CVE-2026-72251

Vulnerability Information
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Vulnerability Title
netfilter: nf_nat_sip: reload possible stale data pointer
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_nat_sip: reload possible stale data pointer quoting sashiko: ------------------------------------------------------------------------ [..] noticed a potential memory bug and header corruption involving the SIP NAT helper. In net/netfilter/nf_nat_sip.c:nf_nat_sip(): if (skb_ensure_writable(skb, skb->len)) { nf_ct_helper_log(skb, ct, "cannot mangle packet"); return NF_DROP; } uh = (void *)skb->data + protoff; uh->dest = ct_sip_info->forced_dport; if (!nf_nat_mangle_udp_packet(skb, ct, ctinfo, protoff, 0, 0, NULL, 0)) { If a cloned or fragmented SKB is reallocated by skb_ensure_writable(), the old data buffer is freed. However, nf_nat_sip() fails to update *dptr to point to the new buffer. It also appears to use nf_nat_mangle_udp_packet() on what could be a TCP packet, which would overwrite the sequence number with a checksum update. ------------------------------------------------------------------------ nf_conntrack_sip linerizes skbs, hence no fragmented skb can be seen. But clones are possible, so rebuild dptr. Disable nf_nat_mangle_udp_packet() branch for TCP streams. It doesn't look like this can ever happen, else we should have received bug reports about this, so just check the conntrack is UDP and drop otherwise. The calling conntrack_sip set ->forced_dport for SIP_HDR_VIA_UDP messages, so I don't think this is ever expected to be true for a TCP stream.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会开源的一个操作系统内核。 Linux kernel存在安全漏洞，该漏洞源于nf_nat_sip函数中skb_ensure_writable重新分配后未更新数据指针，可能导致内存错误和头部损坏。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 7266507d89991fa1e989283e4e032c6d9357fe26 ~ bded21a4bf9bf86a79148be735723a97ca9a7532 -
Linux Linux 3.9 -

II. Public POCs for CVE-2026-72251

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III. Intelligence Information for CVE-2026-72251

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Patches & Fixes for CVE-2026-72251 (7)

Same Patch Batch · Linux · 2026-08-15 · 845 CVEs total

CVE-2026-72407 10.0 CRITICAL geneve: validate inner network offset in geneve_gro_complete()
CVE-2026-72408 10.0 CRITICAL geneve: gate GRO hint in geneve_gro_complete() on gs->gro_hint
CVE-2026-74279 10.0 CRITICAL crypto: cavium/cpt - fix DMA cleanup using wrong loop index
CVE-2026-72421 10.0 CRITICAL ipv4: fib: Don't ignore error route in local/main tables.
CVE-2026-74280 10.0 CRITICAL crypto: marvell/octeontx - fix DMA cleanup using wrong loop index
CVE-2026-74309 10.0 CRITICAL vdpa/octeon_ep: fix IRQ-to-ring mapping in interrupt handler
CVE-2026-74475 10.0 CRITICAL vxlan: use neigh_ha_snapshot() in route_shortcircuit()
CVE-2026-72493 9.9 CRITICAL net: serialize netif_running() check in enqueue_to_backlog()
CVE-2026-72436 9.8 CRITICAL netfilter: ipset: Don't use test_bit() in lockless RCU readers in hash types
CVE-2026-74394 9.8 CRITICAL RDMA/srpt: fix integer overflow in immediate data length check
CVE-2026-72417 9.8 CRITICAL netfilter: flowtable: Validate iph->ihl in nf_flow_ip4_tunnel_proto()
CVE-2026-72069 9.8 CRITICAL locking/rt: Fix the incorrect RCU protection in rt_spin_unlock()
CVE-2026-72422 9.8 CRITICAL ksmbd: fix use-after-free of conn->preauth_info in concurrent SMB2 NEGOTIATE
CVE-2026-72065 9.8 CRITICAL net: mana: Validate the packet length reported by the NIC
CVE-2026-72064 9.8 CRITICAL net: mana: Sync page pool RX frags for CPU
CVE-2026-72429 9.8 CRITICAL ipv6: ioam: fix type confusion of dst_entry
CVE-2026-72249 9.8 CRITICAL netfilter: flowtable: use dst in this direction when pushing IPIP header
CVE-2026-72226 9.8 CRITICAL batman-adv: tt: prevent TVLV OOB check overflow
CVE-2026-72451 9.8 CRITICAL xfrm: Fix xfrm state cache insertion race
CVE-2026-72041 9.8 CRITICAL espintcp: use sk_msg_free_partial to fix partial send

Showing top 20 of 845 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-72251

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