CVE-2022-42336

Cross-guest SSBD bypass via counter underflow

Published May 17, 2023 · Updated Jan 22, 2025

Counter-accounting failure in Xen 4.17 allows guest OS users to leave SSBD inactive for other HVM guests on the same AMD core. Each guest write to VIRT_SPEC_CTRL.SSBD updates a shared per-core counter without verifying that the requested state changed. Underflow saturates the counter, so Xen falsely treats SSBD as active; exploitation requires affected x86 AMD or Hygon hardware and HVM guests.

CVSS severity3.3
Low
EPSS probability0.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Counter-accounting failure in Xen 4.17 allows guest OS users to leave SSBD inactive for other HVM guests on the same AMD core. Each guest write to VIRT_SPEC_CTRL.SSBD updates a shared per-core counter without verifying that the requested state changed. Underflow saturates the counter, so Xen falsely treats SSBD as active; exploitation requires affected x86 AMD or Hygon hardware and HVM guests.

The record

CVE
CVE-2022-42336
Published
May 17, 2023
Updated
Jan 22, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
Unavailable
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 17, 2023CVE publishedPublication date reported by the CVE source.
  2. Jan 22, 2025Record 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 privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

3.3NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
3.3CISA-ADPCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
3.3Canonical UbuntuCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

No sourced classifications are available.

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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