CVE-2026-29646Public exploitNetwork attack vector

Guest privilege-boundary violation via misrouted sie writes

Published Apr 20, 2026 · Updated Apr 20, 2026

Improper privilege management in OpenXiangShan NEMU before 55295c4 allows guest OS users to alter machine interrupt-enable state. With CONFIG_RVH enabled and virtualization active, csr_write routes a VS-mode write to sie through vmode_set_sie, which writes derived bits into mie rather than the virtual supervisor interrupt-enable state. A guest executing a crafted CSR-set instruction can cross the virtualization boundary and corrupt interrupt handling, causing denial of service or a privilege-boundary violation.

CVSS severity9.8
Critical
EPSS probability0.36%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Improper privilege management in OpenXiangShan NEMU before 55295c4 allows guest OS users to alter machine interrupt-enable state. With CONFIG_RVH enabled and virtualization active, csr_write routes a VS-mode write to sie through vmode_set_sie, which writes derived bits into mie rather than the virtual supervisor interrupt-enable state. A guest executing a crafted CSR-set instruction can cross the virtualization boundary and corrupt interrupt handling, causing denial of service or a privilege-boundary violation.

The record

CVE
CVE-2026-29646
Published
Apr 20, 2026
Updated
Apr 20, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-267, T1068
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 20, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

9.8CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-267Privilege Defined With Unsafe Actions
T1068Exploitation for Privilege Escalation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo