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Linux KernelOperating system · Linux

CVE-2023-23455

MEDIUM · 5.5 CVSS v3.1 Published 2023-01-12
Fix available
A fix is available. Upgrade to after 6.1.4 or later.
See remediation →
57/100
Remediation priority · Elevated
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
atm_tc_enqueue in net/sched/sch_atm.c in the Linux kernel through 6.1.4 allows attackers to cause a denial of service because of type confusion (non-negative numbers can sometimes indicate a TC_ACT_SHOT condition rather than valid classification results).

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-843

A resource is accessed as one type when it was actually allocated as another, so the code misreads memory layout — in interpreters and language runtimes this is frequently a direct path to code execution. It often arises from unchecked casts on attacker-influenced objects. The fix is strict type checks before casts and memory-safe access patterns.

General guidance for the type confusion 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:>= 2.6.12, <= 6.1.4
Debian LinuxOperating system
Affected:= 11.0

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
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/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 a release after 6.1.4
Vendor patch git.kernel.org →
Recommended fix High confidence

Linux Kernel 6.1.5 or later (or distribution-specific kernel version that includes the fix)

  1. Identify the current kernel version using `uname -r`
  2. Check if your distribution has released a security update for this CVE (e.g., `apt list --upgradable` or check your vendor's security advisories)
  3. If using upstream kernel, upgrade to kernel version 6.1.5 or later which contains the fix
  4. For Debian 11, apply Debian LTS updates or upgrade to a newer Debian release with updated kernel
  5. Reboot the system to load the new kernel
  6. Verify the fix is applied by checking the kernel version and confirming the sch_atm.c code no longer has the type confusion issue
Caveat Kernel upgrades may require rebuild of out-of-tree modules and can introduce compatibility issues with existing system configurations

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

We can identify the exact fixed release, upgrade, and verify it in staging — typical engagement from $1,600. 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-2023-23455 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
  • No spam, self-promotion, credentials, or personal data