CVE-2026-63937

Summary

In the Linux kernel, the following vulnerability has been resolved: KVM: SEV: Use READ_ONCE() when reading entries/indices from PSC buffer Use READ_ONCE() when reading entries/indices from the guest-accessible Page State Change buffer to defend against TOCTOU bugs. Don't bother with READ_ONCE()/WRITE_ONCE() for cases where KVM is writing (and not consuming the result!), as the guest isn't supposed to touch the buffer while it's being processed. I.e. using READ_ONCE() is all about protecting against misbehaving guests.

Impact & exploitability

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

Affected products we track (1)

Recommendation

Apply the vendor fix promptly. Open any affected product above for its exact safe version.

Official patch: https://git.kernel.org/stable/c/b1dfaa6f7a957726a6800135be3659fbe4bbf2a4 ↗

Additional information

• NVD record
• https://git.kernel.org/stable/c/b1dfaa6f7a957726a6800135be3659fbe4bbf2a4Patch
• https://git.kernel.org/stable/c/bd232801ef1d1fd985d2d4ca3cd1d888303ca86fPatch
• https://git.kernel.org/stable/c/c8cc238093ca6c99267032f6cfe78f59389f3157Patch
• https://git.kernel.org/stable/c/edbbe88f83b524434974e84808d3093199d67c24Patch