In the Linux kernel, the following vulnerability has been resolved:

Buffer overflow in drivers/xen/sys-hypervisor.c

The build id returned by HYPERVISOR_xen_version(XENVER_build_id) is
neither NUL terminated nor a string.

The first causes a buffer overflow as sprintf in buildid_show will
read and copy till it finds a NUL.

00000000 f4 91 51 f4 dd 38 9e 9d 65 47 52 eb 10 71 db 50 |..Q..8..eGR..q.P|
00000010 b9 a8 01 42 6f 2e 32 |...Bo.2|
00000017

So use a memcpy instead of sprintf to have the correct value:

00000000 f4 91 51 f4 dd 00 9e 9d 65 47 52 eb 10 71 db 50 |..Q.....eGR..q.P|
00000010 b9 a8 01 42 |...B|
00000014

(the above have a hack to embed a zero inside and check it's
returned correctly).

This is XSA-485 / CVE-2026-31786

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Advisories
Source ID Title
Debian DLA Debian DLA DLA-4561-1 linux-6.1 security update
Debian DSA Debian DSA DSA-6238-1 linux security update
Debian DSA Debian DSA DSA-6243-1 linux security update
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Wed, 06 May 2026 19:45:00 +0000

Type Values Removed Values Added
Weaknesses CWE-787
CPEs cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:7.1:rc2:*:*:*:*:*:*

Mon, 04 May 2026 08:45:00 +0000


Sun, 03 May 2026 06:30:00 +0000

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}

cvssV3_1

{'score': 7.8, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}


Sat, 02 May 2026 11:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-119

Sat, 02 May 2026 00:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

cvssV3_1

{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}

threat_severity

Important


Thu, 30 Apr 2026 14:00:00 +0000

Type Values Removed Values Added
Weaknesses CWE-119
CWE-170

Thu, 30 Apr 2026 11:30:00 +0000


Thu, 30 Apr 2026 11:15:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: Buffer overflow in drivers/xen/sys-hypervisor.c The build id returned by HYPERVISOR_xen_version(XENVER_build_id) is neither NUL terminated nor a string. The first causes a buffer overflow as sprintf in buildid_show will read and copy till it finds a NUL. 00000000 f4 91 51 f4 dd 38 9e 9d 65 47 52 eb 10 71 db 50 |..Q..8..eGR..q.P| 00000010 b9 a8 01 42 6f 2e 32 |...Bo.2| 00000017 So use a memcpy instead of sprintf to have the correct value: 00000000 f4 91 51 f4 dd 00 9e 9d 65 47 52 eb 10 71 db 50 |..Q.....eGR..q.P| 00000010 b9 a8 01 42 |...B| 00000014 (the above have a hack to embed a zero inside and check it's returned correctly). This is XSA-485 / CVE-2026-31786
Title Buffer overflow in drivers/xen/sys-hypervisor.c
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-05-11T22:15:47.090Z

Reserved: 2026-03-09T15:48:24.141Z

Link: CVE-2026-31786

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Analyzed

Published: 2026-04-30T11:16:20.967

Modified: 2026-05-06T19:44:30.693

Link: CVE-2026-31786

cve-icon Redhat

Severity : Important

Publid Date: 2026-04-30T00:00:00Z

Links: CVE-2026-31786 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-05-06T21:15:13Z

Weaknesses