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Linux KernelOperating system · Linux

CVE-2026-52981

HIGH · 7.5 CVSS v3.1 Published 2026-06-24
Fix available
A fix is available. Upgrade to 6.1.175 / 6.6.141 or later.
See remediation →
84/100
Remediation priority · High
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: neigh: let neigh_xmit take skb ownership neigh_xmit always releases the skb, except when no neighbour table is found. But even the first added user of neigh_xmit (mpls) relied on neigh_xmit to release the skb (or queue it for tx). sashiko reported: If neigh_xmit() is called with an uninitialized neighbor table (for example, NEIGH_ND_TABLE when IPv6 is disabled), it returns -EAFNOSUPPORT and bypasses its internal out_kfree_skb error path. Because the return value of neigh_xmit() is ignored here, does this leak the SKB? Assume full ownership and remove the last code path that doesn't xmit or free skb.

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

The Linux kernel's neigh_xmit function has a memory leak where it fails to free an SKB when returning -EAFNOSUPPORT (e.g., when the neighbor table is uninitialized such as NEIGH_ND_TABLE with IPv6 disabled). The function bypasses its internal out_kfree_skb error path, causing the SKB to leak. The fix removes the code path that neither transmits nor frees the SKB, ensuring full ownership is always assumed.

MitigationApply the kernel patch that ensures neigh_xmit always either transmits or frees the SKB, removing the code path that returns -EAFNOSUPPORT without freeing the SKB. Consider backporting to stable kernels.

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:>= 4.1, < 6.1.175>= 6.2, < 6.6.141>= 6.7, < 6.12.91>= 6.13, < 6.18.33>= 6.19, < 7.0.10= 7.1

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
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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. Check installed kernel version
    Run `uname -r` or `cat /proc/version` to get the kernel version string
    Affected if The version falls within any of these ranges: >= 4.1 and < 6.1.175; >= 6.2 and < 6.6.141; >= 6.7 and < 6.12.91; >= 6.13 and < 6.18.33; >= 6.19 and < 7.0.10; or equals 7.1
  2. Check if IPv6 is disabled in the kernel
    Check the kernel config file (usually /boot/config-$(uname -r) or /proc/config.gz) for CONFIG_IPV6=n, or check runtime status via `cat /proc/sys/net/ipv6/conf/all/disable_ipv6` (value of 1 means disabled)
    Affected if IPv6 is disabled at compile time (CONFIG_IPV6=n) or runtime (disable_ipv6 = 1), as the flaw triggers when NEIGH_ND_TABLE is uninitialized due to IPv6 being disabled
  3. Check for active neighbor entries using the ND table
    Run `ip -6 neigh show` or check `cat /proc/net/ndisc` to see if any IPv6 neighbor discovery entries exist
    Affected if Neighbor entries exist, indicating the code path that can leak SKBs is being exercised (the function neigh_xmit is called during neighbor transmissions)

You are affected if your kernel version is in the affected ranges AND IPv6 is disabled (either at compile time or runtime), causing the NEIGH_ND_TABLE to be uninitialized and triggering the SKB leak in neigh_xmit when neighbor transmissions occur.

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.

dbcve · scoped
Upgrade available Upgrade to 6.1.175 / 6.6.141 / 6.12.91 or later
Fixed in 6.1.1756.6.1416.12.91
Interim mitigation

Apply the kernel patch that ensures neigh_xmit always either transmits or frees the SKB, removing the code path that returns -EAFNOSUPPORT without freeing the SKB. Consider backporting to stable kernels.

Recommended fix High confidence

Upgrade to kernel >= 6.1.175 (for 6.1.x), >= 6.6.141 (for 6.2.x-6.6.x), >= 6.12.91 (for 6.7.x-6.12.x), or >= 6.18.33 (for 6.13.x-6.17.x)

  1. Identify the currently running Linux kernel version using `uname -r`
  2. Determine which version range your current kernel falls into based on the affected versions: >= 4.1 and < 6.1.175, >= 6.2 and < 6.6.141, >= 6.7 and < 6.12.91, or >= 6.13 and < 6.18.33
  3. Upgrade the Linux kernel to a patched version: for 6.1.x line upgrade to >= 6.1.175, for 6.2.x upgrade to >= 6.6.141, for 6.7.x-6.12.x upgrade to >= 6.12.91, or for 6.13.x-6.17.x upgrade to >= 6.18.33
  4. Reboot the system to load the patched kernel
  5. Verify the kernel version after reboot with `uname -r` to confirm the fix is applied
Caveat Kernel upgrades may require rebooting services and could have compatibility implications with custom kernel modules or specific hardware drivers; test in staging before production deployment

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

Fix this in Linux Kernel Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing4.0 h
  • Review / QA2.0 h
10.0 hours of engineering $1,720
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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-2026-52981 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
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