CVE-2026-31786

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> Buffer overflow in drivers/xen/sys-hypervisor.c<br /> <br /> The build id returned by HYPERVISOR_xen_version(XENVER_build_id) is<br /> neither NUL terminated nor a string.<br /> <br /> The first causes a buffer overflow as sprintf in buildid_show will<br /> read and copy till it finds a NUL.<br /> <br /> 00000000 f4 91 51 f4 dd 38 9e 9d 65 47 52 eb 10 71 db 50 |..Q..8..eGR..q.P|<br /> 00000010 b9 a8 01 42 6f 2e 32 |...Bo.2|<br /> 00000017<br /> <br /> So use a memcpy instead of sprintf to have the correct value:<br /> <br /> 00000000 f4 91 51 f4 dd 00 9e 9d 65 47 52 eb 10 71 db 50 |..Q.....eGR..q.P|<br /> 00000010 b9 a8 01 42 |...B|<br /> 00000014<br /> <br /> (the above have a hack to embed a zero inside and check it&amp;#39;s<br /> returned correctly).<br /> <br /> This is XSA-485 / CVE-2026-31786