CVE-2026-29645

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of service disruption.

Exploit odds

0.5% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-04-20 20:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 10:29 UTC Last updatedMost recent change to the record

Details

Published

2026-04-20 20:16 UTC

Last modified

2026-06-17 10:29 UTC

Exploit probability

0.5% · EPSS, next 30 days

Weakness

CWE-131

Record status

Analyzed

Affected

• Xiangshan Nemu 2025.12

Attack profile CVSS 3.1 · 7.5

Attack vector

Network

Complexity

Low

Privileges needed

None

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High