CVE-2026-64580: Linux

High severity, CVSS 7.8. EPSS: 0.2% chance of exploitation in the next 30 days.

In the Linux kernel, the following vulnerability has been resolved: xfrm6: clear dst.dev on error to avoid double netdev_put in xfrm6_fill_dst() On the error path where in6_dev_get(dev) returns NULL, xfrm6_fill_dst() releases the device reference with netdev_put() but leaves xdst->u.dst.dev set. dst_destroy() later calls netdev_put(dst->dev) again, so the same net_device reference is released twice, underflowing its refcount (ref_tracker WARNING + "unregister_netdevice: waiting for <dev> to become free"). Clear xdst->u.dst.dev after the netdev_put(), the same way the XFRM device-offload paths xfrm_dev_state_add() and xfrm_dev_policy_add() in net/xfrm/xfrm_device.c NULL ->dev when releasing the reference on error. ref_tracker: reference already released. ref_tracker: allocated in: xfrm6_fill_dst (net/ipv6/xfrm6_policy.c:86) ... udpv6_sendmsg (net/ipv6/udp.c:1696) ... ref_tracker: freed in: xfrm6_fill_dst (net/ipv6/xfrm6_policy.c:90) ... WARNING: lib/ref_tracker.c:322 at ref_tracker_free+0x58b/0x780 dst_destroy (net/core/dst.c:115) rcu_core handle_softirqs ...

Affected products

• Linux Linux: from 3.0.79, before 3.1 (fixed in 3.1); from 3.2.46, before 3.3 (fixed in 3.3); from 3.4.46, before 3.5 (fixed in 3.5); from 3.9.3, before 3.10 (fixed in 3.10); from 3.10, before 6.1.183 (fixed in 6.1.183); from 6.2, before 6.6.148 (fixed in 6.6.148); …

Published 2026-08-05. Last modified 2026-08-19.