CVE-2023-34325

Guest-to-host escalation via libfsimage stack overflow

Published Jan 5, 2024 · Updated Nov 4, 2025

Stack buffer overflow in Xen libfsimage affects all Xen versions and allows guest OS users using pygrub to gain host control. Pygrub passes guest-controlled disk images to libfsimage, whose legacy XFS parsing code writes beyond a stack buffer while inspecting crafted filesystem data. Exploitation requires a guest configured to boot with pygrub; successful corruption raises the guest to domain-construction-tool privileges, normally control of the host.

CVSS severity7.8
High
EPSS probability0.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stack buffer overflow in Xen libfsimage affects all Xen versions and allows guest OS users using pygrub to gain host control. Pygrub passes guest-controlled disk images to libfsimage, whose legacy XFS parsing code writes beyond a stack buffer while inspecting crafted filesystem data. Exploitation requires a guest configured to boot with pygrub; successful corruption raises the guest to domain-construction-tool privileges, normally control of the host.

The record

CVE
CVE-2023-34325
Published
Jan 5, 2024
Updated
Nov 4, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-787, T1611
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 5, 2024CVE publishedPublication date reported by the CVE source.
  2. Nov 4, 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

7.8CISA-ADPCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/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)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1611Escape to Host

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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