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Linux KernelOperating system · Linux

CVE-2026-52970

MEDIUM · 5.5 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 →
57/100
Remediation priority · Elevated
Zero-click Patch available 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: netfilter: nft_ct: fix missing expect put in obj eval nft_ct_expect_obj_eval() allocates an expectation and may call nf_ct_expect_related(), but never drops its local reference. Add nf_ct_expect_put(exp) before return to balance allocation.

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 nft_ct_expect_obj_eval() function in the Linux kernel's netfilter nftables module allocates a connection tracking expectation and may call nf_ct_expect_related(), but fails to release its local reference count via nf_ct_expect_put() before returning. This creates an unbalanced reference count, leading to a memory leak of the expectation object.

MitigationApply the kernel patch adding nf_ct_expect_put(exp) before each return path in nft_ct_expect_obj_eval() to balance the allocation, or update to a kernel version containing this fix.

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:>= 5.3, < 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= 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
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

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 kernel version
    Run 'uname -r' or 'cat /proc/version' and compare the installed kernel version against the affected ranges: >= 5.3, < 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; = 7.1
    Affected if The installed kernel version falls within any of these ranges
  2. Verify nftables is active
    Run 'nft list ruleset' or check if the nft command is available and the nftables kernel module is loaded via 'lsmod | grep nft'
    Affected if nftables is loaded and actively processing rules
  3. Check for ct expectation usage in nftables rules
    Run 'nft list ruleset | grep -i ct' or specifically look for 'ct expect' or 'expect' statements within nftables rule definitions
    Affected if Rules contain ct expectation objects (nftables rules using the 'expect' keyword for connection tracking expectations)
  4. Monitor for nf_conntrack_expect memory leak
    Check /proc/slabinfo or use 'grep expect /proc/meminfo' over time to observe growing memory consumption in the nf_conntrack_expect cache, or use 'cat /proc/net/stat/nf_conntrack_expect' if available
    Affected if The nf_conntrack_expect slab cache grows persistently without being freed, indicating the memory leak is occurring

You are affected if your kernel version is in the affected range AND nftables is running with ct expectation rules, as the leak only occurs when the vulnerable code path in nft_ct_expect_obj_eval() is triggered.

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 5.10.258 / 5.15.209 / 6.1.175 or later
Fixed in 5.10.2585.15.2096.1.175
Vendor patch git.kernel.org →
Interim mitigation

Apply the kernel patch adding nf_ct_expect_put(exp) before each return path in nft_ct_expect_obj_eval() to balance the allocation, or update to a kernel version containing this fix.

Recommended fix High confidence

5.10.258, 5.15.209, 6.1.175, or 6.6.141 (depending on which branch is in use)

  1. Identify the current running kernel version using `uname -r`
  2. Determine which kernel branch is in use (e.g., 5.10.x, 5.15.x, 6.1.x, or 6.6.x)
  3. Upgrade to a fixed kernel version: for 5.10.x use >= 5.10.258, for 5.15.x use >= 5.15.209, for 6.1.x use >= 6.1.175, or for 6.6.x use >= 6.6.141
  4. Reboot the system to load the new kernel
  5. Verify the kernel version after reboot with `uname -r`
Caveat Kernel upgrades may require matching system utilities and drivers; ensure compatibility with your distribution before upgrading

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-2026-52970 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
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  • Version or environment caveats, and links to real fixes
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