State corruption via wildcarded RVV instruction decoding
Published Apr 20, 2026 · Updated Apr 20, 2026
Instruction validation in OpenXiangShan NEMU before 2025.12.r2 allows attackers to corrupt emulator state via a crafted RISC-V binary. The RVV decode table wildcards funct3 for vsetvli, vsetivli, and vsetvl instead of requiring 111, so reserved OP-V encodings execute as configuration instructions rather than trap. Exploitation requires NEMU to run attacker-supplied RISC-V code and can cause incorrect traps, architectural divergence, or a service interruption.
Summary
What happened
Instruction validation in OpenXiangShan NEMU before 2025.12.r2 allows attackers to corrupt emulator state via a crafted RISC-V binary. The RVV decode table wildcards funct3 for vsetvli, vsetivli, and vsetvl instead of requiring 111, so reserved OP-V encodings execute as configuration instructions rather than trap. Exploitation requires NEMU to run attacker-supplied RISC-V code and can cause incorrect traps, architectural divergence, or a service interruption.
The record
- CVE
- CVE-2026-29645
- Published
- Apr 20, 2026
- Updated
- Apr 20, 2026
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-131, CWE-1287
- Attack vector
- network
- Privileges
- unauthenticated
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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Is a vulnerable build present?
What conditions does exploitation require?
What is affected?
Affected products and versions are unavailable in this record.
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
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
- Crafted invalid OP-V instruction reproducerproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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