CVE Catalog

CVE-2026-63829

HighCVSS 8.8
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.12%

3th percentile - higher than 3% of all known CVEs

Summary

Vulnerability in the Linux kernel ip_gre driver allows a user with CAP_NET_ADMIN in one network namespace to modify a GRE tunnel in another namespace where they lack privileges. Missing CAP_NET_ADMIN check in the target namespace.

Risk Assessment

An attacker can alter tunnel configuration in another namespace, potentially leading to traffic interception or network disruption.

Recommendation

Apply the Linux kernel patch that adds rtnl_dev_link_net_capable() check in ipgre_changelink() and erspan_changelink().

Other vulnerabilities in Linux kernel

See all
Original NVD description (English source)

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.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS