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Linux KernelOperating system · Linux

CVE-2026-23456

HIGH · 8.2 CVSS v3.1 Published 2026-04-03
Fix available
A fix is available. Upgrade to 5.10.253 / 5.15.203 or later.
See remediation →
91/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_h323: fix OOB read in decode_int() CONS case In decode_int(), the CONS case calls get_bits(bs, 2) to read a length value, then calls get_uint(bs, len) without checking that len bytes remain in the buffer. The existing boundary check only validates the 2 bits for get_bits(), not the subsequent 1-4 bytes that get_uint() reads. This allows a malformed H.323/RAS packet to cause a 1-4 byte slab-out-of-bounds read. Add a boundary check for len bytes after get_bits() and before get_uint().

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis
How this class of weakness works · CWE-125

The code reads past the end (or before the start) of a buffer, returning memory that was never meant to be exposed. Attackers use it to leak secrets like keys or to defeat memory-protection defences. Remediation is validating indices and lengths before every read.

General guidance for the out-of-bounds read class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 2.6.17, < 5.10.253>= 5.11, < 5.15.203>= 5.16, < 6.1.167>= 6.2, < 6.6.130>= 6.7, < 6.12.78>= 6.13, < 6.18.20>= 6.19, < 6.19.10= 7.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 5.10.253 / 5.15.203 / 6.1.167 or later
Fixed in 5.10.2535.15.2036.1.167
Vendor patch git.kernel.org →
Recommended fix High confidence

5.10.253, 5.15.203, 6.1.167, or 6.6.130 (depending on which kernel series is currently in use)

  1. 1. Identify the currently running Linux kernel version using 'uname -r'
  2. 2. Check which major kernel series your system is running (e.g., 5.10, 5.15, 6.1, 6.6)
  3. 3. For systems running kernel 5.10.x: upgrade to kernel version 5.10.253 or later
  4. 4. For systems running kernel 5.11-5.15.x: upgrade to kernel version 5.15.203 or later
  5. 5. For systems running kernel 5.16-6.1.x: upgrade to kernel version 6.1.167 or later
  6. 6. For systems running kernel 6.2-6.6.x: upgrade to kernel version 6.6.130 or later
  7. 7. For systems running kernel 6.7+: verify if the fix is included by checking kernel release notes or the commit 1e3a3593162c96e8a8de48b1e14f60c3b57fca8a
  8. 8. After upgrading the kernel, reboot the system to load the fixed version
Caveat Upgrading kernel versions may require system reboot and could introduce compatibility issues with custom kernel modules or proprietary drivers; ensure backup and test in staging environment first

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $3,200. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-23456 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
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