CVE-2026-53269
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Synproxy Hook Reference Counting Race Condition in Linux Kernel

Vulnerability report for CVE-2026-53269, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.

Publication date: 2026-06-25

Last updated on: 2026-07-08

Assigner: kernel.org

Description

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.

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Meta Information

Published
2026-06-25
Last Modified
2026-07-08
Generated
2026-07-15
AI Q&A
2026-06-25
EPSS Evaluated
2026-07-14
NVD
EUVD

Affected Vendors & Products

Showing 13 associated CPEs
Vendor Product Version / Range
linux linux_kernel 7.1
linux linux_kernel 7.1
linux linux_kernel 7.1
linux linux_kernel 7.1
linux linux_kernel From 5.16 (inc) to 6.1.176 (exc)
linux linux_kernel From 6.2 (inc) to 6.6.143 (exc)
linux linux_kernel From 5.11 (inc) to 5.15.210 (exc)
linux linux_kernel From 6.13 (inc) to 6.18.36 (exc)
linux linux_kernel From 6.7 (inc) to 6.12.94 (exc)
linux linux_kernel From 6.19 (inc) to 7.0.13 (exc)
linux linux_kernel 7.1
linux linux_kernel 7.1
linux linux_kernel From 5.3 (inc) to 5.10.259 (exc)

Helpful Resources

Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability exists in the Linux kernel's netfilter synproxy component. The issue arises because the synproxy infrastructure registers netfilter hooks on-demand when a user adds the first iptables target or nftables expression. If multiple such registrations happen concurrently, they can race each other, leading to potential inconsistencies.

To fix this, a mutex was introduced to serialize access to the reference counting control blocks from both frontends, preventing race conditions during hook registration.

Impact Analysis

This vulnerability can lead to race conditions during the registration of netfilter hooks in the Linux kernel. Such race conditions might cause instability or unexpected behavior in the kernel's packet filtering mechanisms, potentially affecting network security or system reliability.

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