CVE-2026-97477 RDMA/counter: Fix num_counters leak on bind_qp failure in alloc_and_bind()
A resource leak in the Linux kernel RDMA counter module allows attackers to permanently block port mode switching, causing denial of service.
- 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-2026-97477?
CVE-2026-97477 is a denial of service vulnerability in Linux, published on 24 Sep 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:
RDMA/counter: Fix num_counters leak on bind_qp failure in alloc_and_bind()
When __rdma_counter_bind_qp() fails in alloc_and_bind(), the error path jumps to err_mode which frees the counter without decrementing port_counter->num_counters. The only place that decrements is rdma_counter_free(), which is unreachable since the counter was never successfully bound.
This leak accumulates across repeated failures, permanently preventing the port from switching to AUTO mode (-EBUSY in __counter_set_mode()) and blocking the MANUAL→NONE auto-revert in rdma_counter_free(). When the mode was NONE before the call, the MANUAL mode set by __counter_set_mode() also leaks since the revert logic is never reached.
Add an err_bind label between the num_counters increment and the existing err_mode label. It decrements num_counters and mirrors the MANUAL→NONE revert from rdma_counter_free(), ensuring the port state is fully restored on bind failure.
Which versions are affected by CVE-2026-97477?
How do I fix CVE-2026-97477?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-97477 being exploited?
There is no known exploitation of CVE-2026-97477 in the wild and no public exploit code.
Sources
Also known as AZL-103781, BELL-CVE-2026-97477, DEBIAN-CVE-2026-97477, GHSA-8gp2-fhh5-vxhw, UBUNTU-CVE-2026-97477.