CVE-2025-27465

x86: Incorrect stubs exception handling for flags recovery

Published Jul 16, 2025 CVSS 3.1 · 4.3 Medium EPSS < 1% KEV · Not listed
Description
Certain instructions need intercepting and emulating by Xen. In some
cases Xen emulates the instruction by replaying it, using an executable
stub. Some instructions may raise an exception, which is supposed to be
handled gracefully. Certain replayed instructions have additional logic
to set up and recover the changes to the arithmetic flags.

For replayed instructions where the flags recovery logic is used, the
metadata for exception handling was incorrect, preventing Xen from
handling the the exception gracefully, treating it as fatal instead.

Remediation

Vendor Workaround

There are no mitigations.

Tracking

Sign in to view the affected projects.

Advisories

Source ID Title
Debian DSA Debian DSA DSA-6068-1 xen security update
EUVD EUVD EUVD-2025-21593 Certain instructions need intercepting and emulating by Xen. In some cases Xen emulates the instruction by replaying it, using an executable stub. Some instructions may raise an exception, which is supposed to be handled gracefully. Certain replayed instructions have additional logic to set up and recover the changes to the arithmetic flags. For replayed instructions where the flags recovery logic is used, the metadata for exception handling was incorrect, preventing Xen from handling the the exception gracefully, treating it as fatal instead.
History
Type Values Removed Values Added
CPEs cpe:2.3:o:xen:xen:*:*:*:*:*:*:x86:*
Type Values Removed Values Added
Weaknesses CWE-755
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N'}

cvssV3_1

{'score': 4.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L'}

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N'}

ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Metrics epss

{'score': 0.00018}

Type Values Removed Values Added
Description Certain instructions need intercepting and emulating by Xen. In some cases Xen emulates the instruction by replaying it, using an executable stub. Some instructions may raise an exception, which is supposed to be handled gracefully. Certain replayed instructions have additional logic to set up and recover the changes to the arithmetic flags. For replayed instructions where the flags recovery logic is used, the metadata for exception handling was incorrect, preventing Xen from handling the the exception gracefully, treating it as fatal instead.
Title x86: Incorrect stubs exception handling for flags recovery
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
XEN
Published
Updated
Nov 4, 2025, 9:09 PM
Reserved
Feb 26, 2025, 9:16 AM
Status
Analyzed
Published
Jul 16, 2025, 9:15 AM
Modified
Jun 17, 2026, 9:03 AM