Medium [CVE-2026-72239] Revert "Drop WBINVD before setting MSR_AMD64_SYSCFG_SNP_EN"
This medium-severity Red Hat Linux advisory covers CVE-2026-72239.
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Summary
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. ] A flaw was found in the Linux kernel, specifically within the Secure Encrypted Virtualization-Secure Nested Paging (SEV-SNP) feature.
This vulnerability involves a timing issue, or race condition, during the process of clearing processor caches. If not handled correctly, this can lead to a situation where critical memory regions, known as Real Mode Protection (RMP) tables, are not properly synchronized across processors.
- < 8.8
Official advisory · high-confidence parse· fetched 24 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 24 days ago·verify at source
Mitigation
The source record does not include mitigation steps. That is not a statement that no fix exists — read the vendor advisory below for the authoritative guidance.
Official advisory · high-confidence parse· fetched 24 days ago·verify at source
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