CVE-2026-29645 Details
Description
NEMU (OpenXiangShan/NEMU) before v2025.12.r2 contains an improper instruction-validation flaw in its RISC-V Vector (RVV) decoder. The decoder does not correctly validate the funct3 field when decoding vsetvli/vsetivli/vsetvl, allowing certain invalid OP-V instruction encodings to be misinterpreted and executed as vset* configuration instructions rather than raising an illegal-instruction exception. This can be exploited by providing crafted RISC-V binaries to cause incorrect trap behavior, architectural state corruption/divergence, and potential denial of service in systems that rely on NEMU for correct execution or sandboxing.
A vulnerability exists in NEMU (OpenXiangShan/NEMU) versions prior to v2025.12.r2, where the RISC-V Vector decoder improperly validates the funct3 field for the vsetvli, vsetivli, and vsetvl instructions. This flaw allows certain invalid OP-V instruction encodings to be misinterpreted as valid vset* configuration instructions, instead of triggering an illegal-instruction exception. Exploitation involves using crafted RISC-V binaries, which can lead to incorrect trap behavior, corruption or divergence of architectural state, and potential denial-of-service in environments that depend on NEMU for accurate execution or sandboxing.
Users can update to NEMU version v2025.12.r2 or later, where this vulnerability has been fixed.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed Apr 21, 2026References to Advisories, Solutions, and Tools
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Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-1287 | Improper Validation of Specified Type of Input | CISA-ADP |
| CWE-131 | Incorrect Calculation of Buffer Size | CISA-ADP |
Affected Products
| Product | Versions |
|---|---|
| xiangshan nemu | 2025.12 r1 |
CPE
Remediation
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Change History
5 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jun 17, 2026 | CVE Modified | [email protected] |
| Jun 17, 2026 | CVE Modified | CISA-ADP |
| Apr 24, 2026 | Initial Analysis | [email protected] |
| Apr 21, 2026 | CVE Modified | CISA-ADP |
| Apr 20, 2026 | New CVE Received | [email protected] |