CVE-2026-43233Network attack vector

Remote kernel crash via H.323 length over-read

Published May 6, 2026 · Updated May 6, 2026

Out-of-bounds read in the H.323 conntrack helper in Linux Kernel allows remote attackers to crash the kernel via crafted Q.931 traffic. In decode_choice(), a boundary check passes the zero-initialized len value before get_len() dereferences one or two bytes beyond a fully consumed PER buffer. Exploitation requires the nf_conntrack_h323 helper to be active; the read is limited to two bytes, with no reported write or code execution.

CVSS severity8.2
High
EPSS probability0.46%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds read in the H.323 conntrack helper in Linux Kernel allows remote attackers to crash the kernel via crafted Q.931 traffic. In decode_choice(), a boundary check passes the zero-initialized len value before get_len() dereferences one or two bytes beyond a fully consumed PER buffer. Exploitation requires the nf_conntrack_h323 helper to be active; the read is limited to two bytes, with no reported write or code execution.

The record

CVE
CVE-2026-43233
Published
May 6, 2026
Updated
May 6, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-125, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 6, 2026CVE publishedPublication date reported by the CVE source.
  2. May 6, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=4.15
  2. Affected versionversion=ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa <2a3aac4205e7d2f1aca2e3827de8cdd517d36c4a
  3. Affected versionversion=ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa <35f1943d242e1b9f0b6e91c0c93bfb293a9f8224
  4. Affected versionversion=ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa <53d32735d77ab56cc3fc7bd53a7d099418f19be1
  5. Affected versionversion=ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa <7ef82863d42261817a6394c6c881bd6757a70f16
  6. Affected versionversion=ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa <81f2fc5b0d0cf4696146f00f837596d10b92dead
  7. Affected versionversion=ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa <baed0d9ba91d4f390da12d5039128ee897253d60
  8. Affected versionversion=ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa <bcb50aa0b8f2b74a9fe5a1c7bee6f2657a288041
  9. Affected versionversion=ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa <f0a83d0a4b7c127d32ac06d607a9214937716129

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=4.15; version=ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa <2a3aac4205e7d2f1aca2e3827de8cdd517d36c4a; version=ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa <35f1943d242e1b9f0b6e91c0c93bfb293a9f8224; version=ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa <53d32735d77ab56cc3fc7bd53a7d099418f19be1; version=ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa <7ef82863d42261817a6394c6c881bd6757a70f16; version=ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa <81f2fc5b0d0cf4696146f00f837596d10b92dead; version=ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa <baed0d9ba91d4f390da12d5039128ee897253d60; version=ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa <bcb50aa0b8f2b74a9fe5a1c7bee6f2657a288041; version=ec8a8f3c31ddef0a7d9626c4b8a4baa30f3b80aa <f0a83d0a4b7c127d32ac06d607a9214937716129

Published CVSS scores

8.2kernel.orgCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-125Out-of-bounds Read
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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