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Linux KernelOperating system · Linux

CVE-2026-53269

MEDIUM · 5.5 CVSS v3.1 Published 2026-06-25
Fix available
A fix is available. Upgrade to 5.10.259 / 5.15.210 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: synproxy: add mutex to guard hook reference counting As the synproxy infrastructure register netfilter hooks on-demand when a user adds the first iptables target or nftables expression, if done concurrently they can race each other. Introduce a mutex to serialize the refcount control blocks access from both frontends. While a per namespace mutex might be more efficient, it is not needed for target/expression like SYNPROXY.

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

A detailed technical summary for this CVE is being prepared.

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, < 5.10.259>= 5.11, < 5.15.210>= 5.16, < 6.1.176>= 6.2, < 6.6.143>= 6.7, < 6.12.94>= 6.13, < 6.18.36>= 6.19, < 7.0.13= 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

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 5.10.259 / 5.15.210 / 6.1.176 or later
Fixed in 5.10.2595.15.2106.1.176
Vendor patch git.kernel.org →
Recommended fix High confidence

Linux Kernel 5.10.259, 5.15.210, 6.1.176, or 6.6.143 (depending on which branch you are on)

  1. 1. Identify the currently running kernel version using `uname -r`
  2. 2. Determine which stable kernel branch your current version belongs to based on the affected ranges (>= 5.3, < 5.10.259; >= 5.11, < 5.15.210; >= 5.16, < 6.1.176; >= 6.2, < 6.6.143)
  3. 3. Upgrade to the first fixed version in your branch: for 5.10.x upgrade to 5.10.259+, for 5.11-5.15.x upgrade to 5.15.210+, for 5.16-6.1.x upgrade to 6.1.176+, for 6.2-6.6.x upgrade to 6.6.143+
  4. 4. On Debian/Ubuntu: `apt-get update && apt-get dist-upgrade` or install specific kernel package
  5. 5. On RHEL/CentOS: `yum update kernel`
  6. 6. On Fedora: `dnf update kernel`
  7. 7. Reboot the system to load the new kernel: `systemctl reboot`
  8. 8. Verify the new kernel version is running and contains the fix using `uname -r` and checking for the synproxy mutex commit
Caveat Kernel upgrades may require rebooting services and could introduce regressions in drivers or modules; test in staging environment before production deployment

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 $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-2026-53269 in production — separate from our analysis above.

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What this is

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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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