CVE-2026-31786
Buffer overflow in drivers/xen/sys-hypervisor.c
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
INFO
Published Date :
April 30, 2026, 11:16 a.m.
Last Modified :
April 30, 2026, 5:11 p.m.
Remotely Exploit :
No
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Solution
- Update the Linux kernel to a patched version.
- Ensure the build ID copy is properly terminated.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-31786.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-31786 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-31786
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-31786 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-31786 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Apr. 30, 2026
Action Type Old Value New Value 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 Added Reference https://git.kernel.org/stable/c/4b4defd2fce3f966c25adabf46644a85558f1169 Added Reference https://git.kernel.org/stable/c/52cecff98bda2c51eed1c6ce9d21c5d6268fb19d Added Reference https://git.kernel.org/stable/c/5c5ff7c7bd15bb536f44b10b3fb5b8408f344d0a Added Reference https://git.kernel.org/stable/c/8288d031a01dbacfde3fc643f7be3d23504de64d Added Reference https://git.kernel.org/stable/c/d5f59216650c51e5e3fcb7517c825bc8047f60ef Added Reference https://git.kernel.org/stable/c/e3af585e1728c917682b6a3de9a69b41fb9194d4 Added Reference https://git.kernel.org/stable/c/f458ba102da97fafca106327086fc95f3fc764cb -
CVE Modified by af854a3a-2127-422b-91ae-364da2661108
Apr. 30, 2026
Action Type Old Value New Value Added Reference http://www.openwall.com/lists/oss-security/2026/04/28/12 Added Reference http://xenbits.xen.org/xsa/advisory-485.html