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
Updated2026-05-06 19:44:30 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: 0.000120000 probability, percentile 0.015390000 (date 2026-05-05)

Problem Types: CWE-787

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

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Linux Linux Kernel All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 84b7625728ea311ea35bdaa0eded53c1c56baeaa e3af585e1728c917682b6a3de9a69b41fb9194d4 git Not specified
CNA Linux Linux affected 84b7625728ea311ea35bdaa0eded53c1c56baeaa 8288d031a01dbacfde3fc643f7be3d23504de64d git Not specified
CNA Linux Linux affected 84b7625728ea311ea35bdaa0eded53c1c56baeaa f458ba102da97fafca106327086fc95f3fc764cb git Not specified
CNA Linux Linux affected 84b7625728ea311ea35bdaa0eded53c1c56baeaa 4b4defd2fce3f966c25adabf46644a85558f1169 git Not specified
CNA Linux Linux affected 84b7625728ea311ea35bdaa0eded53c1c56baeaa 5c5ff7c7bd15bb536f44b10b3fb5b8408f344d0a git Not specified
CNA Linux Linux affected 84b7625728ea311ea35bdaa0eded53c1c56baeaa d5f59216650c51e5e3fcb7517c825bc8047f60ef git Not specified
CNA Linux Linux affected 84b7625728ea311ea35bdaa0eded53c1c56baeaa 52cecff98bda2c51eed1c6ce9d21c5d6268fb19d git Not specified
CNA Linux Linux affected 84b7625728ea311ea35bdaa0eded53c1c56baeaa 27fdbab4221b375de54bf91919798d88520c6e28 git Not specified
CNA Linux Linux affected 4.13 Not specified
CNA Linux Linux unaffected 4.13 semver 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
CNA Linux Linux unaffected 7.1-rc2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/27fdbab4221b375de54bf91919798d88520c6e28 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/5c5ff7c7bd15bb536f44b10b3fb5b8408f344d0a 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/4b4defd2fce3f966c25adabf46644a85558f1169 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/f458ba102da97fafca106327086fc95f3fc764cb 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/e3af585e1728c917682b6a3de9a69b41fb9194d4 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/52cecff98bda2c51eed1c6ce9d21c5d6268fb19d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
www.openwall.com/lists/oss-security/2026/04/28/12 af854a3a-2127-422b-91ae-364da2661108 www.openwall.com Mailing List, Third Party Advisory
xenbits.xen.org/xsa/advisory-485.html af854a3a-2127-422b-91ae-364da2661108 xenbits.xen.org Mailing List, Third Party Advisory
git.kernel.org/stable/c/8288d031a01dbacfde3fc643f7be3d23504de64d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/d5f59216650c51e5e3fcb7517c825bc8047f60ef 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
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