CVE-2026-72239 x86/virt/sev: Revert "Drop WBINVD before setting MSR_AMD64_SYSCFG_SNP_EN"
A race condition in Linux kernel SEV initialization may leave dirty cache lines unflushed, violating AMD SNP firmware requirements.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-72239?
CVE-2026-72239 is a critical vulnerability in Linux, published on 15 Aug 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:
x86/virt/sev: Revert "Drop WBINVD before setting MSR_AMD64_SYSCFG_SNP_EN"
Revert
99cf1fb58e68 ("x86/virt/sev: Drop WBINVD before setting MSR_AMD64_SYSCFG_SNP_EN").
Section 8.8 of the SNP spec says:
Before invoking SNP_INIT_EX with INIT_RMP set to 1, software must ensure that no CPUs contain dirty cache lines for the memory containing the RMP.
Cachelines can be moved from cache to cache in a dirty state. The wbinvd_on_all_cpus() before SNP_INIT_EX flushes the caches for each CPU, but if the IPIs for WBINVD race with this dirty cacheline movement, it is possible that they may not get flushed, violating the firmware requirement.
Doing wbinvd_on_all_cpus() before setting SNPEn is safer since the RMP table is not yet in use.
[ Heroically bisected by Srikanth. ] [ bp: Massage commit message. ]
Which versions are affected by CVE-2026-72239?
How do I fix CVE-2026-72239?
Apply the vendor's patch.
Is CVE-2026-72239 being exploited?
There is no known exploitation of CVE-2026-72239 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-72239, GHSA-mh7r-v762-68jw, UBUNTU-CVE-2026-72239.