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

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Summary

CVECVE-2026-31786
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-04-30 11:16:20 UTC
Updated2026-05-03 07:16:21 UTC
DescriptionIn 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

Risk And Classification

Primary CVSS: v3.1 7.8 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS: 0.000780000 probability, percentile 0.229230000 (date 2026-05-02)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 e3af585e1728c917682b6a3de9a69b41fb9194d4 git Not specified
CNA Linux Linux affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 8288d031a01dbacfde3fc643f7be3d23504de64d git Not specified
CNA Linux Linux affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 f458ba102da97fafca106327086fc95f3fc764cb git Not specified
CNA Linux Linux affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 4b4defd2fce3f966c25adabf46644a85558f1169 git Not specified
CNA Linux Linux affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 5c5ff7c7bd15bb536f44b10b3fb5b8408f344d0a git Not specified
CNA Linux Linux affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 d5f59216650c51e5e3fcb7517c825bc8047f60ef git Not specified
CNA Linux Linux affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 52cecff98bda2c51eed1c6ce9d21c5d6268fb19d git Not specified
CNA Linux Linux unaffected 5.10.254 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.204 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.170 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.137 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.85 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.26 6.18.* semver Not specified
CNA Linux Linux unaffected 7.0.3 7.0.* semver Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/5c5ff7c7bd15bb536f44b10b3fb5b8408f344d0a 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/4b4defd2fce3f966c25adabf46644a85558f1169 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/f458ba102da97fafca106327086fc95f3fc764cb 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/e3af585e1728c917682b6a3de9a69b41fb9194d4 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/52cecff98bda2c51eed1c6ce9d21c5d6268fb19d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
www.openwall.com/lists/oss-security/2026/04/28/12 af854a3a-2127-422b-91ae-364da2661108 www.openwall.com
xenbits.xen.org/xsa/advisory-485.html af854a3a-2127-422b-91ae-364da2661108 xenbits.xen.org
git.kernel.org/stable/c/8288d031a01dbacfde3fc643f7be3d23504de64d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/d5f59216650c51e5e3fcb7517c825bc8047f60ef 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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