CVE-2026-29649 — CRITICAL (9.8)

Vulnerability Description

NEMU contains an implementation flaw in its RISC-V Hypervisor CSR handling where henvcfg[7:4] (CBIE/CBCFE/CBZE-related fields) is incorrectly masked/updated based on menvcfg[7:4], so a machine-mode write to menvcfg can implicitly modify the hypervisor's environment configuration. This can lead to incorrect enforcement of virtualization configuration and may cause unexpected traps or denial of service when executing cache-block management instructions in virtualized contexts (V=1).

CVSS Score

9.8

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality

HIGH

Integrity

HIGH

Availability

HIGH

Affected Products

Vendor	Product	Versions
Xiangshan	Nemu	-

Related Weaknesses (CWE)

CWE-693

References

https://docs.riscv.org/reference/isa/priv/hypervisor.htmlProduct
https://docs.riscv.org/reference/isa/priv/machine.htmlProduct
https://github.com/OpenXiangShan/NEMU/issues/681Issue Tracking
https://github.com/OpenXiangShan/NEMU/pull/689Issue TrackingPatch

FAQ

What is CVE-2026-29649?

CVE-2026-29649 is a vulnerability with a CVSS score of 9.8 (CRITICAL). NEMU contains an implementation flaw in its RISC-V Hypervisor CSR handling where henvcfg[7:4] (CBIE/CBCFE/CBZE-related fields) is incorrectly masked/updated based on menvcfg[7:4], so a machine-mode wr...

How severe is CVE-2026-29649?

CVE-2026-29649 has been rated CRITICAL with a CVSS base score of 9.8/10. This is considered a critical vulnerability requiring immediate attention.

Is there a patch for CVE-2026-29649?

Check the references section above for vendor advisories and patch information. Affected products include: Xiangshan Nemu.