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Linux KernelOperating system · Linux

CVE-2026-52993

CRITICAL · 9.8 CVSS v3.1 Published 2026-06-24
Fix available
A fix is available. Upgrade to 5.10.258 / 5.15.209 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click 8 weeks old

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: tipc: fix double-free in tipc_buf_append() tipc_msg_validate() can potentially reallocate the skb it is validating, freeing the old one. In tipc_buf_append(), it was being called with a pointer to a local variable which was a copy of the caller's skb pointer. If the skb was reallocated and validation subsequently failed, the error handling path would free the original skb pointer, which had already been freed, leading to double-free. Fix this by checking if head now points to a newly allocated reassembled skb. If it does, reassign *headbuf for later freeing operations.

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 · high confidence

Double-free vulnerability in Linux kernel's TIPC (Transparent Inter-Process Communication) subsystem where tipc_buf_append() passes a copy of an skb pointer to tipc_msg_validate(). When validation reallocates the skb (freeing the old one) and subsequent validation fails, the error path attempts to free the original pointer which was already freed, causing double-free.

MitigationApply the kernel patch which adds a check to determine if head points to a newly allocated reassembled skb and reassigns *headbuf appropriately for subsequent freeing operations. This is a kernel-level fix requiring rebuild of the affected kernel/module.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

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:>= 4.15, < 5.10.258>= 5.11, < 5.15.209>= 5.16, < 6.1.175>= 6.2, < 6.6.141>= 6.7, < 6.12.91>= 6.13, < 6.18.33>= 6.19, < 7.0.10

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
High
Integrity
High
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Verify TIPC kernel module is loaded
    Run 'lsmod | grep tipc' to list loaded TIPC module, or check /proc/modules for 'tipc' entry
    Affected if The tipc module appears in the loaded module list (module is active)
  2. Check kernel version against patch date
    Run 'uname -r' to get kernel version; compare against the version that includes the fix for CVE-2026-52993 (the patch addresses the double-free in tipc_buf_append when tipc_msg_validate fails after reallocation)
    Affected if Kernel version is older than the version containing the CVE-2026-52993 fix
  3. Detect active TIPC sockets
    Run 'ss -x | grep tipc' or check /proc/net/tipc* files for active TIPC connections; also check 'netstat -x | grep tipc' if available
    Affected if Any TIPC sockets or connections are listed (indicates TIPC protocol is in use)
  4. Verify TIPC kernel configuration
    Check /boot/config-$(uname -r) or /proc/config.gz for CONFIG_TIPC=m (module) or CONFIG_TIPC=y (built-in)
    Affected if TIPC is enabled in kernel config (CONFIG_TIPC is set to m or y)

User is affected if running a vulnerable kernel version AND the TIPC module is loaded AND TIPC sockets/connections exist in the environment.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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.

From vendor data
Upgrade available Upgrade to 5.10.258 / 5.15.209 / 6.1.175 or later
Fixed in 5.10.2585.15.2096.1.175
Interim mitigation

Apply the kernel patch which adds a check to determine if head points to a newly allocated reassembled skb and reassigns *headbuf appropriately for subsequent freeing operations. This is a kernel-level fix requiring rebuild of the affected kernel/module.

Fix this in Linux Kernel Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing16.0 h
  • Review / QA6.0 h
34.0 hours of engineering $5,720
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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-2026-52993 in production — separate from our analysis above.

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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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