Bug 2516321 (CVE-2026-72061)

Summary: CVE-2026-72061 kernel: net: sit: require CAP_NET_ADMIN in the device netns for changelink
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: high    
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. An incorrect permission check in the `ipip6_changelink()` function, which manages IPv6 over IPv4 (SIT) tunnels, allows a local attacker to bypass intended security restrictions. A user with administrative capabilities (`CAP_NET_ADMIN`) in one network namespace (a virtualized network environment) could modify a tunnel configuration in a different network namespace where they do not have the necessary privileges. This could lead to unauthorized changes to network tunnel settings, potentially causing network disruption or unintended routing.
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Description OSIDB Bzimport 2026-08-15 06:06:23 UTC 
In the Linux kernel, the following vulnerability has been resolved:

net: sit: require CAP_NET_ADMIN in the device netns for changelink

ipip6_changelink() operates on at most two netns, dev_net(dev) and the
tunnel link netns t->net. They differ once the device is created in or
moved to a netns other than the one the request runs in. The rtnl
changelink path checks CAP_NET_ADMIN only against dev_net(dev), so a
caller privileged there but not in t->net can rewrite a tunnel that
lives in t->net.

Gate ipip6_changelink() on rtnl_dev_link_net_capable() at its top,
before any attribute is parsed. sit was the one tunnel type not covered
by the recent series that added this check to the other changelink()
handlers.
Comment 1 Keith Grant 2026-08-17 19:12:30 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026081517-CVE-2026-72061-0d04@gregkh/T