CVE-2026-29649

Name: CVE-2026-29649
Creator: NVD / NIST
Published: 2026-04-20T20:16:48.41+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 0.45%

Last modified Jun 17, 2026

CVE-2026-29649 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. 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).. EPSS estimates a 0.45% chance of exploitation in the next 30 days.

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).

Metrics

CVSS 3.1

9.8/10

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

EPSS Probability

0.45%

35.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-693

Affected Software

Vendor	Product	Versions
Xiangshan	Nemu	All versions

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 Tracking, Patch

Timeline

Published: Apr 20, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-29649?

How severe is CVE-2026-29649?

CVE-2026-29649 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 0.45% probability of exploitation in the next 30 days.

How do I fix CVE-2026-29649?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-29649?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST