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CVE-2026-74569— netfilter: nf_conntrack_sip: widen NAT rewrite delta to s32 in sip_help_tcp()

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 2.6.34版本存在安全漏洞，该漏洞源于netfilter nf_conntrack_sip的sip_help_tcp()函数对NAT重写SIP消息大小变化使用s16类型存储，导致差值溢出，可能造成释放后重用。

CVSS 9.8 · Critical EPSS 0.39% · P31

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux f5b321bd37fbec9188feb1f721ab46a5ac0b35da< ed1f9be6dc8e2e280b8725e44ccdc6e0cd38640d affected
f5b321bd37fbec9188feb1f721ab46a5ac0b35da< 1b0843f9e9b9b0b9b4b70d143b67e58163c85b2c affected
f5b321bd37fbec9188feb1f721ab46a5ac0b35da< 32d4abc8923b0d4046fd63ad6e4917872e44eb6d affected
f5b321bd37fbec9188feb1f721ab46a5ac0b35da< 63eea41759fd682229c14e0a2205802b46d106f3 affected
f5b321bd37fbec9188feb1f721ab46a5ac0b35da< c97621a110e386b2dd69e276eb699e1d3cec581d affected
f5b321bd37fbec9188feb1f721ab46a5ac0b35da< f74554e67ccf04d1fa71069e8c9afa2717e40716 affected
f5b321bd37fbec9188feb1f721ab46a5ac0b35da< ef5e2c6555d2bb52dfe0e4053a8c6193f9d83b64 affected
f5b321bd37fbec9188feb1f721ab46a5ac0b35da< db3d0e0e5d4bc5ab4fe445b9f413d1b486508ca5 affected
… +10 more rows
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I. Basic Information for CVE-2026-74569

Vulnerability Information
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Vulnerability Title
netfilter: nf_conntrack_sip: widen NAT rewrite delta to s32 in sip_help_tcp()
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_sip: widen NAT rewrite delta to s32 in sip_help_tcp() sip_help_tcp() stores the size change of each NAT-rewritten SIP message in s16 diff and accumulates it in s16 tdiff, but a single message can grow by more than S16_MAX while the packet stays under the 65535 enlarge_skb() limit: nf_nat_sip() rewrites every matching URI, and a long Contact list expands the message by tens of kilobytes. diff then wraps, and "datalen = datalen + diff - msglen" yields a huge unsigned datalen, so the next iteration's ct_sip_get_header() reads past the linearized skb tail. Widen diff, tdiff and the seq_adjust hook to s32. Both are bounded by the 65535 byte packet limit, and the seqadj core is already s32 (nf_ct_seqadj_set() takes s32), so no previously accepted input is rejected. BUG: KASAN: use-after-free in ct_sip_get_header (net/netfilter/nf_conntrack_sip.c:464) Read of size 1 at addr ffff888010800000 by task ksoftirqd/1/25 ct_sip_get_header (net/netfilter/nf_conntrack_sip.c:464) sip_help_tcp (net/netfilter/nf_conntrack_sip.c:1694) nf_confirm (net/netfilter/nf_conntrack_proto.c:183) nf_hook_slow (net/netfilter/core.c:619) ip6_output (net/ipv6/ip6_output.c:246) ip6_forward (net/ipv6/ip6_output.c:690) ipv6_rcv (net/ipv6/ip6_input.c:351) __netif_receive_skb_one_core (net/core/dev.c:6212) process_backlog (net/core/dev.c:6676) __napi_poll (net/core/dev.c:7735) net_rx_action (net/core/dev.c:7955) handle_softirqs (kernel/softirq.c:622) run_ksoftirqd (kernel/softirq.c:1076) ...
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 2.6.34版本存在安全漏洞，该漏洞源于netfilter nf_conntrack_sip的sip_help_tcp()函数对NAT重写SIP消息大小变化使用s16类型存储，导致差值溢出，可能造成释放后重用。
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 f5b321bd37fbec9188feb1f721ab46a5ac0b35da ~ ed1f9be6dc8e2e280b8725e44ccdc6e0cd38640d -
Linux Linux 2.6.34 -

II. Public POCs for CVE-2026-74569

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III. Intelligence Information for CVE-2026-74569

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Patches & Fixes for CVE-2026-74569 (7)

Same Patch Batch · Linux · 2026-08-15 · 844 CVEs total

CVE-2026-74475 10.0 CRITICAL vxlan: use neigh_ha_snapshot() in route_shortcircuit()
CVE-2026-74280 10.0 CRITICAL crypto: marvell/octeontx - fix DMA cleanup using wrong loop index
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-2026-74309 10.0 CRITICAL vdpa/octeon_ep: fix IRQ-to-ring mapping in interrupt handler
CVE-2026-72408 10.0 CRITICAL geneve: gate GRO hint in geneve_gro_complete() on gs->gro_hint
CVE-2026-72407 10.0 CRITICAL geneve: validate inner network offset in geneve_gro_complete()
CVE-2026-72493 9.9 CRITICAL net: serialize netif_running() check in enqueue_to_backlog()
CVE-2026-72317 9.8 CRITICAL SUNRPC: pin upper rpc_clnt across the TLS connect_worker
CVE-2026-74376 9.8 CRITICAL md/raid10: reset read_slot when reusing r10bio for discard
CVE-2026-72217 9.8 CRITICAL SUNRPC: Bound-check xdr_buf_to_bvec() stores before writing
CVE-2026-72299 9.8 CRITICAL tipc: restrict socket queue dumps in enqueue tracepoints
CVE-2026-74384 9.8 CRITICAL nvme-multipath: fix flex array size in struct nvme_ns_head
CVE-2026-72210 9.8 CRITICAL ntfs: fix off-by-one in mapping pairs decoding bounds checks
CVE-2026-72211 9.8 CRITICAL ntfs: grow index root value before reparent header update
CVE-2026-72209 9.8 CRITICAL ntfs: validate attribute values on lookup
CVE-2026-72046 9.8 CRITICAL gve: fix header buffer corruption with header-split and HW-GRO
CVE-2026-72206 9.8 CRITICAL ntfs: validate index block header more strictly
CVE-2026-74268 9.8 CRITICAL tcp: clear sock_ops cb flags before force-closing a child socket
CVE-2026-74267 9.8 CRITICAL net/sched: sch_codel: Do not call qdisc_tree_reduce_backlog during peek before restoring q

Showing top 20 of 844 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-74569

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