Xen PV Guest Non-SELFSNOOP CPU Memory Corruption

Xen: PV guest on non-SELFSNOOP CPUs can validate non-coherent L2 pagetable I'm not sure whether there are any major users of unshimmed Xen PV left, but https://xenbits.xen.org/docs/unstable/support-matrix.html says it's still a security-supported usecase for 64-bit guests. Tested on Debian's Xen...

CVE-2021-28703

grant table v2 status pages may remain accessible after de-allocation take two Guest get permitted access to certain Xen-owned pages of memory. The majority of such pages remain allocated / associated with a guest for its entire lifetime. Grant table v2 status pages, however, get de-allocated whe...

CVE-2019-19580

An issue was discovered in Xen through 4.12.x allowing x86 PV guest OS users to gain host OS privileges by leveraging race conditions in pagetable promotion and demotion operations, because of an incomplete fix for CVE-2019-18421. XSA-299 addressed several critical issues in restartable PV type...

Further issues with restartable PV type change operations

ISSUE DESCRIPTION XSA-299 addressed several critical issues in restartable PV type change operations. Despite extensive testing and auditing, some corner cases were missed. IMPACT A malicious PV guest administrator may be able to escalate their privilege to that of the host. VULNERABLE SYSTEMS Al...