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Vulnerabilities

Vulnerability · CVE-2026-29645

NEMU (OpenXiangShan/NEMU) before v2025.12.r2 contains an improper instruction-validation flaw in its RISC-V Vector (RVV) decoder.

Published Apr 20, 2026 · catalog updated Jun 17, 2026 · NEMU (OpenXiangShan/NEMU) before v2025.12.r2

Check if you run it

No confirmed exploitation is on record for CVE-2026-29645. EPSS is 0.74%. Act only if a listed version of NEMU (OpenXiangShan/NEMU) before v2025.12.r2 is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (NEMU (OpenXiangShan/NEMU) before v2025.12.r2).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High7.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.74%
Remediation
Advisory link
Affected products
cpe xiangshan/nemu

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe xiangshan/nemu2025.12

How to fix CVE-2026-29645

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-29645. EPSS is 0.74%. Act only if a listed version of NEMU (OpenXiangShan/NEMU) before v2025.12.r2 is installed.

Which versions are affected?

Compare what you have installed with 2025.12. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-1287; CWE-131. EPSS 0.74%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Apr 20, 2026 · NIST NVD

    Detected

    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

  2. Jun 17, 2026 · NIST NVD

    Updated

    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

Sources

  • CVE.orgVulnerability recordCVE-2026-29645

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-29645

    30-day exploitation probability 0.7%

    first.org
  • NIST NVDVulnerability recordCVE-2026-29645

    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

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.