CVE-2026-29646
Published: April 20, 2026· Updated: Apr 21, 2026
Official 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.
Risk Analysis
This critical vulnerability in OpenXiangShan NEMU, when running with the RVH (Hypervisor extension) enabled, allows a guest to incorrectly influence the machine-level interrupt enable state. This breaks privilege and virtualization isolation, potentially leading to denial of service or privilege escalation. The CVSS score of 9.8 highlights the severe impact and ease of exploitation.
No public exploit is currently known for this remotely exploitable vulnerability. The attack complexity is low, making it a significant risk if an exploit emerges.
Ensure NEMU is updated to a version beyond commit 55295c4 to address the incorrect handling of VS-mode guest writes to the supervisor interrupt-enable CSR (sie).
Technical Analysis
CVE-2026-29646 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.
The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.
A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 9.8.
CVSS v3.1 Vector Breakdown
Exploit & PoC Resources
All References (7)
Quick Facts
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2026-29646 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts