CVE-2026-72491: Linux Vulnerability (CVSS 9.8)

Description

In the Linux kernel, the following vulnerability has been resolved: net/9p: fix race condition on rdma->state in trans_rdma.c The rdma->state field is modified without holding req_lock in both recv_done() and p9_cm_event_handler(), while rdma_request() accesses the same field under the req_lock spinlock. This inconsistent locking creates a race condition: - recv_done() running in softirq completion context sets rdma->state = P9_RDMA_FLUSHING without acquiring req_lock - p9_cm_event_handler() modifies rdma->state at multiple points (ADDR_RESOLVED, ROUTE_RESOLVED, ESTABLISHED, CLOSED) without req_lock - rdma_request() uses spin_lock_irqsave(&rdma->req_lock, flags) to protect the read-modify-write of rdma->state The race can cause lost state transitions: recv_done() or the CM event handler could set state to FLUSHING/CLOSED while rdma_request() is concurrently checking or modifying state under the lock, leading to the FLUSHING transition being silently overwritten by CLOSING. This corrupts the connection state machine and can cause use-after-free on RDMA request objects during teardown. Fix by adding req_lock protection to all rdma->state modifications in recv_done() and p9_cm_event_handler(), matching the pattern already used in rdma_request(). Use spin_lock_irqsave/spin_unlock_irqrestore in the CM event handler since it can race with recv_done() which runs in softirq context. Tested with a kernel module that races two threads (simulating rdma_request and recv_done/CM handler) on rdma->state with proper locking: 5.5M+ FLUSHING writes over 27M iterations with 0 lost transitions.

Metrics

CVSS 3.1

9.8/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

0.22%

12.8th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
Linux	Linux	>= 473c7dd1d7b59ff8f88a5154737e3eac78a96e5b, < 4cee2b8766045059d5e0b8114837b4a8efe827ac; >= 473c7dd1d7b59ff8f88a5154737e3eac78a96e5b, < 5424138848eb7d7d8a7196676e90a2cbf2142454; >= 473c7dd1d7b59ff8f88a5154737e3eac78a96e5b, < 3970a19a80de530b801b6256354d4a529a9a2d6c; >= 473c7dd1d7b59ff8f88a5154737e3eac78a96e5b, < 8aadc136d8e8d8fc95d7982d213cfe2234dfcf2b; >= 473c7dd1d7b59ff8f88a5154737e3eac78a96e5b, < 151f8cf5b23d8a534d884432a82a6d54d5a61989; >= 473c7dd1d7b59ff8f88a5154737e3eac78a96e5b, < 13bf9879b778b2f4b260b45bed18f31806120d1e; >= 473c7dd1d7b59ff8f88a5154737e3eac78a96e5b, < ebbcbe5c0db215feecc17def06178da443f4eea6; >= 473c7dd1d7b59ff8f88a5154737e3eac78a96e5b, < 7d54894a1ee265a72d70f7cae1da6cc774cccc71; 3479b3c35e82ed10aa0ca2ee9e78c4eded06ba62; c01ddaa54d7411e964ffd250c018d8469c5852f2; 9e69c673fe077b8dc491cd8406c9bdcb1f76dee2; e48e7e27e4dfd00c81e0381e7cee610cce021452; >= 4.4.185, < 4.5; >= 4.9.185, < 4.10; >= 4.14.132, < 4.15; >= 4.19.57, < 4.20
Linux	Linux	4.20

References

Timeline

Published: Aug 15, 2026
Last Modified: Aug 17, 2026
Status: Received

Frequently Asked Questions

What is CVE-2026-72491?

In the Linux kernel, the following vulnerability has been resolved: net/9p: fix race condition on rdma->state in trans_rdma.c The rdma->state field is modified without holding req_lock in both recv_done() and p9_cm_event_handler(), while rdma_request() accesses the same field under the req_lock spinlock. This inconsistent locking creates a race condition: - recv_done() running in softirq completion context sets rdma->state = P9_RDMA_FLUSHING without acquiring req_lock - p9_cm_event_handler() modifies rdma->state at multiple points (ADDR_RESOLVED, ROUTE_RESOLVED, ESTABLISHED, CLOSED) without req_lock - rdma_request() uses spin_lock_irqsave(&rdma->req_lock, flags) to protect the read-modify-write of rdma->state The race can cause lost state transitions: recv_done() or the CM event handler could set state to FLUSHING/CLOSED while rdma_request() is concurrently checking or modifying state under the lock, leading to the FLUSHING transition being silently overwritten by CLOSING. This corrupts the connection state machine and can cause use-after-free on RDMA request objects during teardown. Fix by adding req_lock protection to all rdma->state modifications in recv_done() and p9_cm_event_handler(), matching the pattern already used in rdma_request(). Use spin_lock_irqsave/spin_unlock_irqrestore in the CM event handler since it can race with recv_done() which runs in softirq context. Tested with a kernel module that races two threads (simulating rdma_request and recv_done/CM handler) on rdma->state with proper locking: 5.5M+ FLUSHING writes over 27M iterations with 0 lost transitions.

How severe is CVE-2026-72491?

CVE-2026-72491 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 0.22% probability of exploitation in the next 30 days.

How do I fix CVE-2026-72491?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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