Privilege-boundary bypass via missing ENVCFG access check
Published Apr 20, 2026 · Updated Apr 20, 2026
Improper privilege management in OpenXiangShan NEMU allows remote authenticated users to read or write privileged CSRs. With Smstateen enabled and mstateen0.ENVCFG cleared, the CSR access check permits henvcfg and senvcfg access instead of raising an illegal-instruction exception. Exploitation requires less-privileged code execution in a multi-privilege or virtualized RISC-V workload, where the bypass defeats intended state-enable isolation.
Summary
What happened
Improper privilege management in OpenXiangShan NEMU allows remote authenticated users to read or write privileged CSRs. With Smstateen enabled and mstateen0.ENVCFG cleared, the CSR access check permits henvcfg and senvcfg access instead of raising an illegal-instruction exception. Exploitation requires less-privileged code execution in a multi-privilege or virtualized RISC-V workload, where the bypass defeats intended state-enable isolation.
The record
- CVE
- CVE-2026-29648
- Published
- Apr 20, 2026
- Updated
- Apr 20, 2026
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-269, T1068
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Apr 20, 2026CVE publishedPublication date reported by the CVE source.
- Apr 20, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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What is affected?
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Published CVSS scores
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Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- ENVCFG in mstateen0 Does Not Control Accessproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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