docs.riscv.org
https://docs.riscv.org/reference/isa/priv/hypervisor.html CVE-2026-29646
CRITICAL
OpenXiangShan NEMU Supervisor Interrupt Enable Register Write Handling Vulnerability
Record summary
CVE-2026-29646 has a selected CVSS score of 9.8 (critical).
Description
In OpenXiangShan NEMU prior to 55295c4, when running with RVH (Hypervisor extension) enabled, a VS-mode guest write to the supervisor interrupt-enable CSR (sie) may be handled incorrectly and can influence machine-level interrupt enable state (mie). This breaks privilege/virtualization isolation and can lead to denial of service or privilege-boundary violation in environments relying on NEMU for correct interrupt virtualization.
Description source: CVE List
Exploitation context
CISA SSVC decision
ExploitationNone
AutomatableYes
Technical impactTotal
CISA Coordinator · SSVC 2.0.3 · Evaluated Apr 21, 2026 · Source: CVE List
References
8docs.riscv.org
https://docs.riscv.org/reference/isa/priv/machine.html docs.riscv.org
https://docs.riscv.org/reference/isa/priv/supervisor.html docs.riscv.org
https://docs.riscv.org/reference/isa/unpriv/zicsr.html github.com
https://github.com/OpenXiangShan/NEMU/issues/951 github.com
https://github.com/OpenXiangShan/NEMU/pull/938 github.com
https://github.com/OpenXiangShan/NEMU/pull/938/commits/55295c46580456d8d5a9d5736e1fda924b8825ab nvd.nist.gov
https://nvd.nist.gov/vuln/detail/CVE-2026-29646