CVE-2026-31786High· 7.8▾ TwilightIn 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 cau…
▾ Twilight zone — High severity, or a signal on a lesser flaw
impact 42.9 · likelihood 0 · exploitation 0
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Stakeholder-Specific Vulnerability Categorization from CISA's ADP record at CVE.org: whether exploitation is observed, whether an attack can be automated, and how much of the system is at stake. The CVSS score shown above comes from the assigning CNA record, not NVD.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via CVEORG
Last analysed / modified upstream
0.2%
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
Linux >= 84b7625728ea311ea35bdaa0eded53c1c56baeaa < e3af585e1728c917682b6a3de9a69b41fb9194d4Linux >= 84b7625728ea311ea35bdaa0eded53c1c56baeaa < 8288d031a01dbacfde3fc643f7be3d23504de64dLinux >= 84b7625728ea311ea35bdaa0eded53c1c56baeaa < f458ba102da97fafca106327086fc95f3fc764cbLinux >= 84b7625728ea311ea35bdaa0eded53c1c56baeaa < 4b4defd2fce3f966c25adabf46644a85558f1169Linux >= 84b7625728ea311ea35bdaa0eded53c1c56baeaa < 5c5ff7c7bd15bb536f44b10b3fb5b8408f344d0aLinux >= 84b7625728ea311ea35bdaa0eded53c1c56baeaa < d5f59216650c51e5e3fcb7517c825bc8047f60efLinux >= 84b7625728ea311ea35bdaa0eded53c1c56baeaa < 52cecff98bda2c51eed1c6ce9d21c5d6268fb19dLinux >= 84b7625728ea311ea35bdaa0eded53c1c56baeaa < 27fdbab4221b375de54bf91919798d88520c6e28Linux 4.13Refer to the linked advisories for vendor-supplied fixes and affected version ranges.
Connected by shared product, vendor, weakness, or advisory.
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