CVE-2026-29643Public exploit

Core hang via invalid CSR shadow write

Published Apr 20, 2026 · Updated Apr 20, 2026

Improper exception handling in XiangShan allows local users to hang a processor core through crafted CSR operations. NewCSR performs shadow writes to custom PMA CSRs absent from csrRwMap; the resulting illegal-instruction exception fails to enter mtvec. Execution in machine mode on the affected core is required, and the demonstrated consequence is disrupted control flow and core unavailability rather than data disclosure.

CVSS severity7.1
High
EPSS probability0.16%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper exception handling in XiangShan allows local users to hang a processor core through crafted CSR operations. NewCSR performs shadow writes to custom PMA CSRs absent from csrRwMap; the resulting illegal-instruction exception fails to enter mtvec. Execution in machine mode on the affected core is required, and the demonstrated consequence is disrupted control flow and core unavailability rather than data disclosure.

The record

CVE
CVE-2026-29643
Published
Apr 20, 2026
Updated
Apr 20, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-703, T1499.004
Attack vector
local
Privileges
Unavailable

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

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesUnavailable in this record.

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.1CISA-ADPCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/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.

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No observations available

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

Weakness, pattern, technique

CWE-703Improper Check or Handling of Exceptional Conditions
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

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

Technologies

Your stack

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Your stack

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