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CVE-2026-72247— netfilter: nf_conncount: fix zone comparison in tuple dedup

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 4.18版本存在安全漏洞，该漏洞源于netfilter nf_conncount的元组去重逻辑中连接跟踪区域比较错误，将区域方向位掩码错误地作为方向参数传递，导致不同区域可能被视为相等，可能导致连接计数不准确。

CVSS 7.5 · High EPSS 0.70% · P52

Possible ATT&CK Techniques 1 AI

T1562

Affected Version Matrix 21

VendorProduct Version RangeStatus
Linux Linux 21ba8847f857028dc83a0f341e16ecc616e34740< 82fc35e0da9a91db9a034f8311f18f77a599ae3f affected
21ba8847f857028dc83a0f341e16ecc616e34740< 78b5d6dbc860776161f9e9206b06ff8a01f531ab affected
21ba8847f857028dc83a0f341e16ecc616e34740< 4f30a89c0ed2418719a1144881c2635b940b543d affected
21ba8847f857028dc83a0f341e16ecc616e34740< 7bdc3c0985ecf17b957811fedcc684acdf698acc affected
21ba8847f857028dc83a0f341e16ecc616e34740< 35a56e2a46b90e6bd4ca816b80e9cb8d20dfc3ce affected
21ba8847f857028dc83a0f341e16ecc616e34740< 3cd9a5792cbea81139c24320986dd0db69e9b5d0 affected
21ba8847f857028dc83a0f341e16ecc616e34740< 6ff07ac5405bea4d4ead3559fc123f987576424a affected
21ba8847f857028dc83a0f341e16ecc616e34740< f62c41b4910e65da396ec9a8c40c1fe7fe82e449 affected
… +13 more rows
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I. Basic Information for CVE-2026-72247

Vulnerability Information
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Vulnerability Title
netfilter: nf_conncount: fix zone comparison in tuple dedup
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conncount: fix zone comparison in tuple dedup The "already exists" dedup logic in __nf_conncount_add() decides whether a connection has already been counted and can be skipped instead of incrementing the connlimit count. It compares the conntrack zone of a list entry with the zone of the connection being added using nf_ct_zone_id() and nf_ct_zone_equal(), passing conn->zone.dir or zone->dir as the direction argument. Those helpers take enum ip_conntrack_dir values: IP_CT_DIR_ORIGINAL is 0 and IP_CT_DIR_REPLY is 1. However, zone->dir is a u8 bitmask: NF_CT_ZONE_DIR_ORIG is 1, NF_CT_ZONE_DIR_REPL is 2 and NF_CT_DEFAULT_ZONE_DIR is 3. Passing that bitmask as the enum direction shifts the meaning of every non-zero value. An ORIG-only zone passes 1 and is tested as REPLY, while REPL-only and default zones pass 2 or 3 and test bits beyond the valid direction range. In those cases nf_ct_zone_id() can fall back to NF_CT_DEFAULT_ZONE_ID instead of using the real zone id, so different zones can be treated as equal and dedup collapses to tuple equality alone. nf_conncount stores and compares the original-direction tuple for a connection. If an skb already has an attached conntrack entry, get_ct_or_tuple_from_skb() explicitly copies ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple, regardless of the packet's ctinfo. Therefore the zone comparison in the tuple dedup path must use IP_CT_DIR_ORIGINAL as well; the zone direction bitmask describes where a zone id applies, not which direction this conncount tuple represents. Fix the two dedup comparisons by passing IP_CT_DIR_ORIGINAL directly. Do not special-case NF_CT_DEFAULT_ZONE_DIR and do not compare raw zone ids: using the existing helpers with IP_CT_DIR_ORIGINAL preserves the direction-aware NF_CT_DEFAULT_ZONE_ID fallback. A default bidirectional zone contains the ORIG bit, so it naturally returns the real zone id; reply-only zones continue to fall back for original-direction tuple comparisons.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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 4.18版本存在安全漏洞，该漏洞源于netfilter nf_conncount的元组去重逻辑中连接跟踪区域比较错误，将区域方向位掩码错误地作为方向参数传递，导致不同区域可能被视为相等，可能导致连接计数不准确。
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 21ba8847f857028dc83a0f341e16ecc616e34740 ~ 82fc35e0da9a91db9a034f8311f18f77a599ae3f -
Linux Linux 4.18 -

II. Public POCs for CVE-2026-72247

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III. Intelligence Information for CVE-2026-72247

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Patches & Fixes for CVE-2026-72247 (8)

Same Patch Batch · Linux · 2026-08-15 · 844 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-2026-74475 10.0 CRITICAL vxlan: use neigh_ha_snapshot() in route_shortcircuit()
CVE-2026-74309 10.0 CRITICAL vdpa/octeon_ep: fix IRQ-to-ring mapping in interrupt handler
CVE-2026-72493 9.9 CRITICAL net: serialize netif_running() check in enqueue_to_backlog()
CVE-2026-74495 9.8 CRITICAL igbvf: Fix leak in TX DMA error cleanup
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-2026-72251 9.8 CRITICAL netfilter: nf_nat_sip: reload possible stale data pointer
CVE-2026-72249 9.8 CRITICAL netfilter: flowtable: use dst in this direction when pushing IPIP header
CVE-2026-72046 9.8 CRITICAL gve: fix header buffer corruption with header-split and HW-GRO
CVE-2026-72226 9.8 CRITICAL batman-adv: tt: prevent TVLV OOB check overflow
CVE-2026-72041 9.8 CRITICAL espintcp: use sk_msg_free_partial to fix partial send

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-2026-72247

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