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CVE-2026-43233— netfilter: nf_conntrack_h323: fix OOB read in decode_choice()

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decode_choice函数中边界检查使用未初始化的len变量，可能导致越界读取。

CVSS 8.2 · High EPSS 0.46% · P38

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa< bcb50aa0b8f2b74a9fe5a1c7bee6f2657a288041 affected
ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa< 2a3aac4205e7d2f1aca2e3827de8cdd517d36c4a affected
ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa< 81f2fc5b0d0cf4696146f00f837596d10b92dead affected
ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa< 7ef82863d42261817a6394c6c881bd6757a70f16 affected
ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa< 53d32735d77ab56cc3fc7bd53a7d099418f19be1 affected
ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa< f0a83d0a4b7c127d32ac06d607a9214937716129 affected
ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa< 35f1943d242e1b9f0b6e91c0c93bfb293a9f8224 affected
ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa< baed0d9ba91d4f390da12d5039128ee897253d60 affected
… +10 more rows
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I. Basic Information for CVE-2026-43233

Vulnerability Information
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Vulnerability Title
netfilter: nf_conntrack_h323: fix OOB read in decode_choice()
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_h323: fix OOB read in decode_choice() In decode_choice(), the boundary check before get_len() uses the variable `len`, which is still 0 from its initialization at the top of the function: unsigned int type, ext, len = 0; ... if (ext || (son->attr & OPEN)) { BYTE_ALIGN(bs); if (nf_h323_error_boundary(bs, len, 0)) /* len is 0 here */ return H323_ERROR_BOUND; len = get_len(bs); /* OOB read */ When the bitstream is exactly consumed (bs->cur == bs->end), the check nf_h323_error_boundary(bs, 0, 0) evaluates to (bs->cur + 0 > bs->end), which is false. The subsequent get_len() call then dereferences *bs->cur++, reading 1 byte past the end of the buffer. If that byte has bit 7 set, get_len() reads a second byte as well. This can be triggered remotely by sending a crafted Q.931 SETUP message with a User-User Information Element containing exactly 2 bytes of PER-encoded data ({0x08, 0x00}) to port 1720 through a firewall with the nf_conntrack_h323 helper active. The decoder fully consumes the PER buffer before reaching this code path, resulting in a 1-2 byte heap-buffer-overflow read confirmed by AddressSanitizer. Fix this by checking for 2 bytes (the maximum that get_len() may read) instead of the uninitialized `len`. This matches the pattern used at every other get_len() call site in the same file, where the caller checks for 2 bytes of available data before calling get_len().
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/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decode_choice函数中边界检查使用未初始化的len变量，可能导致越界读取。
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 ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa ~ bcb50aa0b8f2b74a9fe5a1c7bee6f2657a288041 -
Linux Linux 4.15 -

II. Public POCs for CVE-2026-43233

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III. Intelligence Information for CVE-2026-43233

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Patches & Fixes for CVE-2026-43233 (8)

Same Patch Batch · Linux · 2026-05-06 · 224 CVEs total

CVE-2026-43186 9.8 CRITICAL ipv6: ioam: fix heap buffer overflow in __ioam6_fill_trace_data()
CVE-2026-43185 9.8 CRITICAL ksmbd: fix signededness bug in smb_direct_prepare_negotiation()
CVE-2026-43125 9.8 CRITICAL dlm: validate length in dlm_search_rsb_tree
CVE-2026-43208 9.8 CRITICAL net: do not pass flow_id to set_rps_cpu()
CVE-2026-43198 9.8 CRITICAL tcp: fix potential race in tcp_v6_syn_recv_sock()
CVE-2026-43114 9.4 CRITICAL netfilter: nft_set_pipapo_avx2: don't return non-matching entry on expiry
CVE-2026-43117 9.1 CRITICAL btrfs: tracepoints: get correct superblock from dentry in event btrfs_sync_file()
CVE-2026-43083 9.1 CRITICAL net: ioam6: fix OOB and missing lock
CVE-2026-43197 9.1 CRITICAL netconsole: avoid OOB reads, msg is not nul-terminated
CVE-2026-43232 8.8 HIGH net: wan: farsync: Fix use-after-free bugs caused by unfinished tasklets
CVE-2026-43215 8.8 HIGH cifs: Fix locking usage for tcon fields
CVE-2026-43112 8.8 HIGH fs/smb/client: fix out-of-bounds read in cifs_sanitize_prepath
CVE-2026-43113 8.8 HIGH wifi: wl1251: validate packet IDs before indexing tx_frames
CVE-2026-43110 8.8 HIGH wifi: brcmfmac: validate bsscfg indices in IF events
CVE-2026-43187 8.8 HIGH xfs: delete attr leaf freemap entries when empty
CVE-2026-43283 8.8 HIGH net: ethernet: ec_bhf: Fix dma_free_coherent() dma handle
CVE-2026-43172 8.8 HIGH wifi: iwlwifi: fix 22000 series SMEM parsing
CVE-2026-43239 8.8 HIGH smb: client: prevent races in ->query_interfaces()
CVE-2026-43176 8.8 HIGH wifi: rtw89: pci: validate release report content before using for RTL8922DE
CVE-2026-43249 8.8 HIGH 9p/xen: protect xen_9pfs_front_free against concurrent calls

Showing top 20 of 224 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-43233

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