An issue (known as XSA-212) was discovered in Xen, with fixes available for 4.8.x, 4.7.x, 4.6.x, 4.5.x, and 4.4.x. The earlier XSA-29 fix introduced an insufficient check on XENMEM_exchange input, allowing the caller to drive hypervisor memory accesses outside of the guest provided input/output arrays.
Exploitability
AV:LAC:LPR:HUI:NScope
S:CImpact
C:HI:HA:H8.2/CVSS:3.0/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H