CVE-2021-29795

Host crash via crafted hypercall sequence

Published Sep 21, 2021 · Updated Sep 17, 2024

Denial of service in IBM PowerVM Hypervisor FW860, FW930, FW940, and FW950 allows local users to crash the system from a partition. IBM has not disclosed which hypercall handler or validation error causes the crafted call sequence to terminate the host. Exploitation requires total control of a guest partition and interrupts every virtual machine running on the same physical system.

CVSS severity6.0
Medium
EPSS probability0.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in IBM PowerVM Hypervisor FW860, FW930, FW940, and FW950 allows local users to crash the system from a partition. IBM has not disclosed which hypercall handler or validation error causes the crafted call sequence to terminate the host. Exploitation requires total control of a guest partition and interrupts every virtual machine running on the same physical system.

The record

CVE
CVE-2021-29795
Published
Sep 21, 2021
Updated
Sep 17, 2024
Vendor
IBM
Product
PowerVM Hypervisor
Classifications
CWE-74, T1499.004
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Sep 21, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 17, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=FW860
  2. Affected versionversion=FW930
  3. Affected versionversion=FW940
  4. Affected versionversion=FW950

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

IBM · PowerVM Hypervisorversion=FW860; version=FW930; version=FW940; version=FW950

Published CVSS scores

6.0NIST National Vulnerability DatabaseCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:N/I:N/A:H
6.0IBM CorporationCVSS:3.0/AV:L/AC:L/PR:H/UI:N/S:C/C:N/I:N/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-74Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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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