CVE-2026-68296

Name of the Vulnerable Software and Affected Versions Linux kernel (affected versions not specified)

Description A regression in the GRE tunnel implementation occurs when NETIF F LLTX is converted to the dev->lltx flag. In the functions gre tunnel init() and ip6gre tnl init features(), the assignment of dev->lltx = true is placed after early returns for SEQ or CSUM+encap. This causes GRE, GRETAP, and ip6gre tunnels using these features to lose lockless TX (transmission), leading to the acquisition of xmit lock around ndo start xmit. Because GRE transmission re-enters the network stack via ip tunnel xmit(), holding the xmit lock can result in an ABBA deadlock with the underlay device.

Recommendations At the moment, there is no information about a newer version that contains a fix for this vulnerability.