Bug 2492718 (CVE-2026-53269)

Summary: CVE-2026-53269 kernel: netfilter: synproxy: add mutex to guard hook reference counting
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's netfilter synproxy component. This vulnerability is caused by a race condition during the on-demand registration of netfilter hooks. A local user with privileges to modify netfilter rules could exploit this flaw by concurrently adding iptables targets or nftables expressions. This could lead to unexpected behavior or system instability, potentially resulting in a denial of service (DoS).
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-06-25 10:02:08 UTC 
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.
Comment 1 Mauro Matteo Cascella 2026-06-26 09:36:38 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026062518-CVE-2026-53269-bb6e@gregkh/T