High [CVE-2026-63829] require CAP_NET_ADMIN in the device netns for changelink
This high-severity Red Hat Linux advisory covers CVE-2026-63829 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9.
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Summary
In the Linux kernel, the following vulnerability has been resolved: net: ip_gre: require CAP_NET_ADMIN in the device netns for changelink A tunnel 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. Add rtnl_dev_link_net_capable() next to rtnl_get_net_ns_capable() in net/core/rtnetlink.c.
It requires CAP_NET_ADMIN in the link netns and is skipped when the link netns is dev_net(dev), where the rtnl path already checked it. The other patches in this series use the same helper.
Gate ipgre_changelink() and erspan_changelink() with it, at the top of the op before any attribute is parsed, because the parsers update live tunnel fields first. ipgre_netlink_parms() sets t->collect_md before ip_tunnel_changelink() runs. Commit 8b484efd5cb4 ("ip6: vti: Use ip6_tnl.net in vti6_siocdevprivate().") added the same check on the ioctl path.
This adds it on RTM_NEWLINK. A flaw was found in the Linux kernel's IP Generic Routing Encapsulation (ip_gre) component.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative. Check it before change work.
Official advisory · high-confidence parse· fetched 7 days ago·verify at source
- kernel-0:6.12.0-211.63.1.el10_2
- kernel-rt-0:4.18.0-553.171.1.rt7.512.el8_10
- kernel-0:4.18.0-553.171.1.el8_10
- kernel-0:5.14.0-687.55.1.el9_8
- RHSA-2026:76738
- RHSA-2026:75746
- RHSA-2026:75747
- RHSA-2026:76739
Official advisory · high-confidence parse· fetched 7 days ago·verify at source
Mitigation checklist
- Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
Official advisory · high-confidence parse· fetched 7 days ago·verify at source
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