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CVE-2026-23455— netfilter: nf_conntrack_h323: check for zero length in DecodeQ931()

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DecodeQ931函数缺少长度检查，可能导致越界读取。

CVSS 9.1 · Critical EPSS 1.34% · P71

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux 5e35941d990123f155b02d5663e51a24f816b6f3< 2121f5fbe88daff0f1fc5bc47d359426c74b86b0 affected
5e35941d990123f155b02d5663e51a24f816b6f3< 65fa92f79677858b14b9e4b7275f26639afe2710 affected
5e35941d990123f155b02d5663e51a24f816b6f3< 495e97af9e7249ee02b72bb1d0848a6efc3700f4 affected
5e35941d990123f155b02d5663e51a24f816b6f3< f5e4f4e4cdb75ec36802059a94195a31f193da60 affected
5e35941d990123f155b02d5663e51a24f816b6f3< 633e8f87dad32263f6a57dccdb873f042c062111 affected
5e35941d990123f155b02d5663e51a24f816b6f3< 9d00fe7d6d7c5b5f1065a6e042b54f2e44bd6df8 affected
5e35941d990123f155b02d5663e51a24f816b6f3< b652b05d51003ac074b912684f9ec7486231717b affected
5e35941d990123f155b02d5663e51a24f816b6f3< f173d0f4c0f689173f8cdac79991043a4a89bf66 affected
… +10 more rows
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I. Basic Information for CVE-2026-23455

Vulnerability Information
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Vulnerability Title
netfilter: nf_conntrack_h323: check for zero length in DecodeQ931()
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_h323: check for zero length in DecodeQ931() In DecodeQ931(), the UserUserIE code path reads a 16-bit length from the packet, then decrements it by 1 to skip the protocol discriminator byte before passing it to DecodeH323_UserInformation(). If the encoded length is 0, the decrement wraps to -1, which is then passed as a large value to the decoder, leading to an out-of-bounds read. Add a check to ensure len is positive after the decrement.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/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DecodeQ931函数缺少长度检查，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)

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Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 5e35941d990123f155b02d5663e51a24f816b6f3 ~ 2121f5fbe88daff0f1fc5bc47d359426c74b86b0 -
Linux Linux 2.6.17 -

II. Public POCs for CVE-2026-23455

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III. Intelligence Information for CVE-2026-23455

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Same Patch Batch · Linux · 2026-04-03 · 71 CVEs total

CVE-2026-31402 9.8 CRITICAL nfsd: fix heap overflow in NFSv4.0 LOCK replay cache
CVE-2026-23450 9.8 CRITICAL net/smc: fix NULL dereference and UAF in smc_tcp_syn_recv_sock()
CVE-2026-23427 9.8 CRITICAL ksmbd: fix use-after-free in durable v2 replay of active file handles
CVE-2026-23428 9.8 CRITICAL ksmbd: fix use-after-free of share_conf in compound request
CVE-2026-23461 8.8 HIGH Bluetooth: L2CAP: Fix use-after-free in l2cap_unregister_user
CVE-2026-23425 8.8 HIGH KVM: arm64: Fix ID register initialization for non-protected pKVM guests
CVE-2026-23462 8.8 HIGH Bluetooth: HIDP: Fix possible UAF
CVE-2026-23457 8.6 HIGH netfilter: nf_conntrack_sip: fix Content-Length u32 truncation in sip_help_tcp()
CVE-2026-23456 8.2 HIGH netfilter: nf_conntrack_h323: fix OOB read in decode_int() CONS case
CVE-2026-23459 8.2 HIGH ip_tunnel: adapt iptunnel_xmit_stats() to NETDEV_PCPU_STAT_DSTATS
CVE-2026-31393 8.1 HIGH Bluetooth: L2CAP: Validate L2CAP_INFO_RSP payload length before access
CVE-2026-31392 8.1 HIGH smb: client: fix krb5 mount with username option
CVE-2026-23466 7.8 HIGH drm/xe: Open-code GGTT MMIO access protection
CVE-2026-23432 7.8 HIGH mshv: Fix use-after-free in mshv_map_user_memory error path
CVE-2026-31398 7.8 HIGH mm/rmap: fix incorrect pte restoration for lazyfree folios
CVE-2026-23437 7.8 HIGH net: shaper: protect late read accesses to the hierarchy
CVE-2026-23458 7.8 HIGH netfilter: ctnetlink: fix use-after-free in ctnetlink_dump_exp_ct()
CVE-2026-23444 7.8 HIGH wifi: mac80211: always free skb on ieee80211_tx_prepare_skb() failure
CVE-2026-23449 7.8 HIGH net/sched: teql: Fix double-free in teql_master_xmit
CVE-2026-23445 7.8 HIGH igc: fix page fault in XDP TX timestamps handling

Showing top 20 of 71 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-23455

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