CVE-2026-31786
published 2026-04-30CVE-2026-31786: In the Linux kernel, the following vulnerability has been resolved: Buffer overflow in drivers/xen/sys-hypervisor.c The build id returned by…
PriorityP342high7.8CVSS 3.1
AVLACLPRLUINSUCHIHAH
EPSS
0.20%
9.6th percentile
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
Affected
18 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| linux | linux | — | — |
| linux | linux | >= 84b7625728ea311ea35bdaa0eded53c1c56baeaa < e3af585e1728c917682b6a3de9a69b41fb9194d4 | e3af585e1728c917682b6a3de9a69b41fb9194d4 |
| linux | linux | >= 84b7625728ea311ea35bdaa0eded53c1c56baeaa < 8288d031a01dbacfde3fc643f7be3d23504de64d | 8288d031a01dbacfde3fc643f7be3d23504de64d |
| linux | linux | >= 84b7625728ea311ea35bdaa0eded53c1c56baeaa < f458ba102da97fafca106327086fc95f3fc764cb | f458ba102da97fafca106327086fc95f3fc764cb |
| linux | linux | >= 84b7625728ea311ea35bdaa0eded53c1c56baeaa < 4b4defd2fce3f966c25adabf46644a85558f1169 | 4b4defd2fce3f966c25adabf46644a85558f1169 |
| linux | linux | >= 84b7625728ea311ea35bdaa0eded53c1c56baeaa < 5c5ff7c7bd15bb536f44b10b3fb5b8408f344d0a | 5c5ff7c7bd15bb536f44b10b3fb5b8408f344d0a |
| linux | linux | >= 84b7625728ea311ea35bdaa0eded53c1c56baeaa < d5f59216650c51e5e3fcb7517c825bc8047f60ef | d5f59216650c51e5e3fcb7517c825bc8047f60ef |
| linux | linux | >= 84b7625728ea311ea35bdaa0eded53c1c56baeaa < 52cecff98bda2c51eed1c6ce9d21c5d6268fb19d | 52cecff98bda2c51eed1c6ce9d21c5d6268fb19d |
| linux | linux | >= 84b7625728ea311ea35bdaa0eded53c1c56baeaa < 27fdbab4221b375de54bf91919798d88520c6e28 | 27fdbab4221b375de54bf91919798d88520c6e28 |
| linux | linux_kernel | — | — |
| linux | linux_kernel | — | — |
| linux | linux_kernel | >= 4.13 < 5.10.254 | 5.10.254 |
| linux | linux_kernel | >= 5.11 < 5.15.204 | 5.15.204 |
| linux | linux_kernel | >= 5.16 < 6.1.170 | 6.1.170 |
| linux | linux_kernel | >= 6.13 < 6.18.26 | 6.18.26 |
| linux | linux_kernel | >= 6.19 < 7.0.3 | 7.0.3 |
| linux | linux_kernel | >= 6.2 < 6.6.137 | 6.6.137 |
| linux | linux_kernel | >= 6.7 < 6.12.85 | 6.12.85 |
CVSS provenance
nvdv3.17.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
vendor_redhat7.0HIGH
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VulDB
Linux Kernel up to 7.0.2 sys-hypervisor.c buffer overflow (EUVD-2026-26364 / Nessus ID 319709)
vuldb·2026-06-09·CVSS 7.8
CVE-2026-31786 [HIGH] Linux Kernel up to 7.0.2 sys-hypervisor.c buffer overflow (EUVD-2026-26364 / Nessus ID 319709)
A vulnerability has been found in Linux Kernel up to 7.0.2 and classified as critical. Affected is an unknown function of the file drivers/xen/sys-hypervisor.c. The manipulation leads to buffer overflow.
This vulnerability is listed as CVE-2026-31786. The attack must be carried out from within the local network. There is no available exploit.
The affected component should be upgraded.
GHSA
GHSA-7p99-gmjx-2f7r: In the Linux kernel, the following vulnerability has been resolved:
Buffer overflow in drivers/xen/sys-hypervisor
ghsa_unreviewed·2026-04-30·CVSS 7.8
CVE-2026-31786 [HIGH] CWE-787 GHSA-7p99-gmjx-2f7r: In the Linux kernel, the following vulnerability has been resolved:
Buffer overflow in drivers/xen/sys-hypervisor
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
Kernel
Buffer overflow in drivers/xen/sys-hypervisor.c
kernel_security·2026-03-27
CVE-2026-31786 Buffer overflow in drivers/xen/sys-hypervisor.c
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
Fixes: 84b7625728ea ("xen: add sysfs node for hypervisor build id")
Signed-off-by: Frediano Ziglio
Reviewed-by: Juergen Gr
Red Hat
kernel: Buffer overflow in drivers/xen/sys-hypervisor.c
vendor_redhat·2026-04-30·CVSS 7.0
CVE-2026-31786 [HIGH] CWE-170 kernel: Buffer overflow in drivers/xen/sys-hypervisor.c
kernel: Buffer overflow in drivers/xen/sys-hypervisor.c
A flaw was found in the Linux kernel. A buffer overflow vulnerability exists in the Xen hypervisor driver (`drivers/xen/sys-hypervisor.c`). This flaw occurs because the `HYPERVISOR_xen_version(XENVER_build_id)` function returns a build ID that is not properly null-terminated. When the `buildid_show` function attempts to process this non-null-terminated string using `sprintf`, it can read and copy beyond the intended buffer boundary, potentially leading to a denial of service or other unspecified impacts.
Package: kernel (Red Hat Enterprise Linux 10) - Affected
Package: kernel (Red Hat Enterprise Linux 6) - Under investigation
Package: kernel (Red Hat Enterprise Linux 7) - Affected
Package: kernel-rt (Red Hat Enterprise Linux 7) -
No detection rules found.
No public exploits indexed.
https://git.kernel.org/stable/c/27fdbab4221b375de54bf91919798d88520c6e28https://git.kernel.org/stable/c/4b4defd2fce3f966c25adabf46644a85558f1169https://git.kernel.org/stable/c/52cecff98bda2c51eed1c6ce9d21c5d6268fb19dhttps://git.kernel.org/stable/c/5c5ff7c7bd15bb536f44b10b3fb5b8408f344d0ahttps://git.kernel.org/stable/c/8288d031a01dbacfde3fc643f7be3d23504de64dhttps://git.kernel.org/stable/c/d5f59216650c51e5e3fcb7517c825bc8047f60efhttps://git.kernel.org/stable/c/e3af585e1728c917682b6a3de9a69b41fb9194d4https://git.kernel.org/stable/c/f458ba102da97fafca106327086fc95f3fc764cbhttp://www.openwall.com/lists/oss-security/2026/04/28/12http://xenbits.xen.org/xsa/advisory-485.html
2026-04-30
Published