CVE-2026-31539: smb: smbdirect: introduce smbdirect_socket.recv_io.credits.available

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-04-24 · updated 2026-10-19
Weakness: CWE-362

Description

In the Linux kernel, the following vulnerability has been resolved: smb: smbdirect: introduce smbdirect_socket.recv_io.credits.available The logic off managing recv credits by counting posted recv_io and granted credits is racy. That's because the peer might already consumed a credit, but between receiving the incoming recv at the hardware and processing the completion in the 'recv_done' functions we likely have a window where we grant credits, which don't really exist. So we better have a decicated counter for the available credits, which will be incremented when we posted new recv buffers and drained when we grant the credits to the peer.

Affected products

Linux kernel: from 6.18 before 6.18.11; from 6.19 before 6.19.1 — fixed in 6.18.11, 6.19.1

How to fix

Upgrade to a fixed version: Linux kernel 6.18.11, 6.19.1. Check the vendor advisory for mitigations.

References

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