CVE-2026-64115 vsock/vmci: fix UAF when peer resets connection during handshake
A use-after-free vulnerability in the Linux kernel's VMCI transport allows local attackers to execute arbitrary code or escalate privileges via a crafted connection reset.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-64115?
CVE-2026-64115 is a high-severity use after free vulnerability in Linux kernel, published on 19 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
vsock/vmci: fix UAF when peer resets connection during handshake
vmci_transport_recv_connecting_server() returned err = 0 for a peer RST in its default switch arm:
err = pkt->type == VMCI_TRANSPORT_PACKET_TYPE_RST ? 0 : -EINVAL;
That made vmci_transport_recv_listen() skip vsock_remove_pending(), leaving the pending socket on the listener's pending_links with sk_state = TCP_CLOSE while destroy: still dropped the explicit reference taken before schedule_delayed_work().
One second later vsock_pending_work() observed is_pending=true and performed full cleanup: vsock_remove_pending() then the two trailing sock_put(sk) calls -- the first reached refcount 0 and __sk_freed the socket, and the second wrote into the freed object:
BUG: KASAN: slab-use-after-free in refcount_warn_saturate Write of size 4 at addr ffff88800b1cac80 by task kworker Workqueue: events vsock_pending_work
Treat peer RST like any other unexpected packet type (err = -EINVAL). All destroy: arms now return err < 0, so vmci_transport_recv_listen() removes pending from pending_links synchronously and vsock_pending_work() takes the is_pending=false / !rejected branch, dropping only its own work reference. This also closes the multi-packet race Sashiko reported on v2: pending is removed from the list before any subsequent packet can find it.
The pre-existing sk_acceptq_removed() gap on the err < 0 path of vmci_transport_recv_listen() that Sashiko also noted is not introduced or changed by this patch.
Tested on lts-6.12.79 with KASAN: 52/100 unpatched -> 0/100 patched.
Weakness: CWE-416
Which versions are affected by CVE-2026-64115?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-64115?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-64115 being exploited?
There is no known exploitation of CVE-2026-64115 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-64115, DEBIAN-CVE-2026-64115, GHSA-c2c8-f8x2-chfh, UBUNTU-CVE-2026-64115.