CVE-2026-64190 net: team: fix NULL pointer dereference in team_xmit during mode change
A race condition in the Linux kernel team driver allows a local attacker with CAP_NET_ADMIN to crash the system via a NULL pointer dereference.
- 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-2026-64190?
CVE-2026-64190 is a medium-severity vulnerability in Linux kernel, published on 20 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:
net: team: fix NULL pointer dereference in team_xmit during mode change
__team_change_mode() clears team->ops with memset() before restoring safe dummy handlers via team_adjust_ops(). A concurrent team_xmit() running under RCU on another CPU can read team->ops.transmit during this window and call a NULL function pointer, crashing the kernel.
The race requires a mode change (CAP_NET_ADMIN) concurrent with transmit on the team device.
BUG: kernel NULL pointer dereference, address: 0000000000000000 Oops: 0010 [#1] SMP KASAN NOPTI RIP: 0010:0x0 Call Trace: team_xmit (drivers/net/team/team_core.c:1853) dev_hard_start_xmit (net/core/dev.c:3904) __dev_queue_xmit (net/core/dev.c:4871) packet_sendmsg (net/packet/af_packet.c:3109) __sys_sendto (net/socket.c:2265)
The original code assumed that no ports means no traffic, so mode changes could freely memset()/memcpy() the ops. AF_PACKET with forced carrier breaks that assumption.
Prevent the race instead of making it safe: replace memset()/memcpy() with per-field updates that never touch transmit or receive. Those two handlers are managed solely by team_adjust_ops(), which already installs dummies when tx_en_port_count == 0 (always true during mode change since no ports are present). WRITE_ONCE/READ_ONCE prevent store/load tearing on the handler pointers.
synchronize_net() before exit_op() drains in-flight readers that may still reference old mode state from before port removal switched the handlers to dummies.
Weakness: CWE-476
Which versions are affected by CVE-2026-64190?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-64190?
Apply the vendor's patch.
Is CVE-2026-64190 being exploited?
There is no known exploitation of CVE-2026-64190 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-92862, BELL-CVE-2026-64190, DEBIAN-CVE-2026-64190, GHSA-fg66-cp5r-9m26, ROOT-OS-DEBIAN-11-CVE-2026-64190, ROOT-OS-DEBIAN-12-CVE-2026-64190 and 2 more.