Bug 2516459 (CVE-2026-72253)

Summary: CVE-2026-72253 kernel: netfilter: nf_conntrack_sip: validate skb_dst() before accessing it
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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 Session Initiation Protocol (SIP) connection tracking helper. This vulnerability occurs when network traffic control (tc ingress) or Open vSwitch (openvswitch) subsystems are active, and a specific media handling feature (`sip_external_media`) is enabled. The system fails to properly verify network routing information, which can lead to the `sip_external_media` feature being unintentionally disabled, impacting its intended operation.
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Description OSIDB Bzimport 2026-08-15 06:13:39 UTC 
In the Linux kernel, the following vulnerability has been resolved:

netfilter: nf_conntrack_sip: validate skb_dst() before accessing it

tc ingress and openvswitch do not guarantee routing information to be
available. These subsystems use the conntrack helper infrastructure, and
the SIP helper relies on the skb_dst() to be present if
sip_external_media is set to 1 (which is disabled by default as a module
parameter).

This effectively disables the sip_external_media toggle for these
subsystems without resulting in a crash.
Comment 1 Keith Grant 2026-08-18 17:31:50 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026081553-CVE-2026-72253-5b57@gregkh/T