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CVE-2026-43027— netfilter: nf_conntrack_helper: pass helper to expect cleanup

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基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于netfilter nf_conntrack_helper中期望清理时传递NULL指针，可能导致释放后重用。

AI Predicted 7.8 Difficulty: Moderate EPSS 0.13% · P2

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux ac7b848390036dadd4351899d2a23748075916bd< 5cf28d5c8dcbbe8af6d3b145babe491906d7bad1 affected
ac7b848390036dadd4351899d2a23748075916bd< 504ba4168466c91210c45acdc332479cfd5f2da6 affected
ac7b848390036dadd4351899d2a23748075916bd< dc1739eff48e34cc71d4e2f03715493fbcebd8af affected
ac7b848390036dadd4351899d2a23748075916bd< 2cf2737c85a2ba2b52024dafe68ffad2676f97be affected
ac7b848390036dadd4351899d2a23748075916bd< 2c16e4d64dd91227742dfe196a3e7b0568bef65a affected
ac7b848390036dadd4351899d2a23748075916bd< 620f3d14c1ef51d425060a3056ad8dbae8f998a3 affected
ac7b848390036dadd4351899d2a23748075916bd< 90bd7e8501349db3006d21fbc09df9ffcb172965 affected
ac7b848390036dadd4351899d2a23748075916bd< a242a9ae58aa46ff7dae51ce64150a93957abe65 affected
… +10 more rows
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I. Basic Information for CVE-2026-43027

Vulnerability Information
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Vulnerability Title
netfilter: nf_conntrack_helper: pass helper to expect cleanup
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_helper: pass helper to expect cleanup nf_conntrack_helper_unregister() calls nf_ct_expect_iterate_destroy() to remove expectations belonging to the helper being unregistered. However, it passes NULL instead of the helper pointer as the data argument, so expect_iter_me() never matches any expectation and all of them survive the cleanup. After unregister returns, nfnl_cthelper_del() frees the helper object immediately. Subsequent expectation dumps or packet-driven init_conntrack() calls then dereference the freed exp->helper, causing a use-after-free. Pass the actual helper pointer so expectations referencing it are properly destroyed before the helper object is freed. BUG: KASAN: slab-use-after-free in string+0x38f/0x430 Read of size 1 at addr ffff888003b14d20 by task poc/103 Call Trace: string+0x38f/0x430 vsnprintf+0x3cc/0x1170 seq_printf+0x17a/0x240 exp_seq_show+0x2e5/0x560 seq_read_iter+0x419/0x1280 proc_reg_read+0x1ac/0x270 vfs_read+0x179/0x930 ksys_read+0xef/0x1c0 Freed by task 103: The buggy address is located 32 bytes inside of freed 192-byte region [ffff888003b14d00, ffff888003b14dc0)
Source: CVE Program / CVE List V5
CVSS Information
N/A
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基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于netfilter nf_conntrack_helper中期望清理时传递NULL指针，可能导致释放后重用。
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 ac7b848390036dadd4351899d2a23748075916bd ~ 5cf28d5c8dcbbe8af6d3b145babe491906d7bad1 -
Linux Linux 4.14 -

II. Public POCs for CVE-2026-43027

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III. Intelligence Information for CVE-2026-43027

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Patches & Fixes for CVE-2026-43027 (8)

Same Patch Batch · Linux · 2026-05-01 · 146 CVEs total

CVE-2026-43011 9.8 CRITICAL net/x25: Fix potential double free of skb
CVE-2026-43037 9.8 CRITICAL ip6_tunnel: clear skb2->cb[] in ip4ip6_err()
CVE-2026-31705 9.8 CRITICAL ksmbd: fix out-of-bounds write in smb2_get_ea() EA alignment
CVE-2026-43038 9.8 CRITICAL ipv6: icmp: clear skb2->cb[] in ip6_err_gen_icmpv6_unreach()
CVE-2026-43039 9.8 CRITICAL net: ti: icssg-prueth: fix missing data copy and wrong recycle in ZC RX dispatch
CVE-2026-31718 9.8 CRITICAL ksmbd: fix use-after-free in __ksmbd_close_fd() via durable scavenger
CVE-2026-43018 8.8 HIGH Bluetooth: hci_event: fix potential UAF in hci_le_remote_conn_param_req_evt
CVE-2026-31773 8.8 HIGH Bluetooth: SMP: derive legacy responder STK authentication from MITM state
CVE-2026-31739 8.8 HIGH crypto: tegra - Add missing CRYPTO_ALG_ASYNC
CVE-2026-31735 8.8 HIGH iommupt: Fix short gather if the unmap goes into a large mapping
CVE-2026-31717 8.8 HIGH ksmbd: validate owner of durable handle on reconnect
CVE-2026-43048 8.8 HIGH HID: core: Mitigate potential OOB by removing bogus memset()
CVE-2026-31709 8.8 HIGH smb: client: validate the whole DACL before rewriting it in cifsacl
CVE-2026-31706 8.8 HIGH ksmbd: validate num_aces and harden ACE walk in smb_inherit_dacl()
CVE-2026-31712 8.3 HIGH ksmbd: require minimum ACE size in smb_check_perm_dacl()
CVE-2026-31771 8.1 HIGH Bluetooth: hci_event: move wake reason storage into validated event handlers
CVE-2026-31779 8.1 HIGH wifi: iwlwifi: mvm: fix potential out-of-bounds read in iwl_mvm_nd_match_info_handler()
CVE-2026-43051 8.1 HIGH HID: wacom: fix out-of-bounds read in wacom_intuos_bt_irq
CVE-2026-31708 8.1 HIGH smb: client: fix OOB read in smb2_ioctl_query_info QUERY_INFO path
CVE-2026-31695 7.8 HIGH wifi: virt_wifi: remove SET_NETDEV_DEV to avoid use-after-free

Showing top 20 of 146 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-43027

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