CVE-2026-31786

HIGHPre-NVD 7.87.8—
EchelonGraph scoreMEDIUM confidence

Score 7.8 from GitHub Security Advisory (severity: HIGH) published 2026-04-30. NVD baseline CVSS 7.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
7.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 7.8Exploit: NoneExposed: 0

A fix is available — apply it.

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

CVSS v3
7.8
EG Score
7.8(medium)
EPSS
9.7%
KEV
Not listed

Published

April 30, 2026

Last Modified

June 14, 2026

Advisory Details (9)

Auto-updated May 3, 2026
No patch confirmed yet.
generic

XSA-485 - Xen Security Advisories

http://xenbits.xen.org/xsa/advisory-485.html
generic

oss-security - Xen Security Advisory 485 v2 (CVE-2026-31786) - Linux kernel out of bounds read via Xen-related sysfs file

http://www.openwall.com/lists/oss-security/2026/04/28/12
generic

Buffer overflow in drivers/xen/sys-hypervisor.c - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/f458ba102da97fafca106327086fc95f3fc764cb
generic

Buffer overflow in drivers/xen/sys-hypervisor.c - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/e3af585e1728c917682b6a3de9a69b41fb9194d4
generic

Buffer overflow in drivers/xen/sys-hypervisor.c - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/d5f59216650c51e5e3fcb7517c825bc8047f60ef
generic

Buffer overflow in drivers/xen/sys-hypervisor.c - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/8288d031a01dbacfde3fc643f7be3d23504de64d
generic

Buffer overflow in drivers/xen/sys-hypervisor.c - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/5c5ff7c7bd15bb536f44b10b3fb5b8408f344d0a
generic

Buffer overflow in drivers/xen/sys-hypervisor.c - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/52cecff98bda2c51eed1c6ce9d21c5d6268fb19d
generic

Buffer overflow in drivers/xen/sys-hypervisor.c - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/4b4defd2fce3f966c25adabf46644a85558f1169

Vendor Advisories for CVE-2026-31786(4)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(2)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatkernel-0:5.14.0-687.13.1.el9_82026-06-08redhat
linuxKernel @ 5.10.254—osv

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 14× in last 7d / 44× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 133 total refreshes for this CVE.

  1. 2026-07-22 14:08 UTCEPSS rescore
  2. 2026-07-22 14:08 UTCEPSS rescore
  3. 2026-07-21 15:24 UTCEPSS rescore
  4. 2026-07-21 15:24 UTCEPSS rescore
  5. 2026-07-20 17:08 UTCEPSS rescore
  6. 2026-07-20 17:08 UTCEPSS rescore
  7. 2026-07-20 12:02 UTCOSV refresh
  8. 2026-07-19 14:31 UTCEPSS rescore
  9. 2026-07-19 14:31 UTCEPSS rescore
  10. 2026-07-19 02:29 UTCEPSS rescore
  11. 2026-07-18 10:04 UTCEPSS rescore
  12. 2026-07-18 10:04 UTCEPSS rescore
  13. 2026-07-16 17:03 UTCEPSS rescore
  14. 2026-07-16 17:03 UTCEPSS rescore
  15. 2026-07-15 02:00 UTCEPSS rescore
  16. 2026-07-15 02:00 UTCEPSS rescore
  17. 2026-07-13 22:30 UTCEPSS rescore
  18. 2026-07-13 06:13 UTCEPSS rescore
  19. 2026-07-13 06:13 UTCEPSS rescore
  20. 2026-07-12 05:46 UTCEPSS rescore
  21. 2026-07-11 08:27 UTCEPSS rescore
  22. 2026-07-09 19:10 UTCEPSS rescore
  23. 2026-07-08 15:15 UTCEPSS rescore
  24. 2026-07-07 13:46 UTCEPSS rescore
  25. 2026-07-06 16:27 UTCEPSS rescore
Show 75 more
  1. 2026-07-06 16:27 UTCEPSS rescore
  2. 2026-07-06 02:23 UTCEPSS rescore
  3. 2026-07-06 02:23 UTCEPSS rescore
  4. 2026-07-05 02:30 UTCEPSS rescore
  5. 2026-07-04 06:31 UTCEPSS rescore
  6. 2026-07-01 15:06 UTCEPSS rescore
  7. 2026-06-30 23:22 UTCEPSS rescore
  8. 2026-06-29 14:06 UTCEPSS rescore
  9. 2026-06-29 14:06 UTCEPSS rescore
  10. 2026-06-28 14:07 UTCEPSS rescore
  11. 2026-06-28 14:07 UTCEPSS rescore
  12. 2026-06-28 04:56 UTCEPSS rescore
  13. 2026-06-28 04:56 UTCEPSS rescore
  14. 2026-06-27 03:08 UTCEPSS rescore
  15. 2026-06-25 13:49 UTCEPSS rescore
  16. 2026-06-25 13:49 UTCEPSS rescore
  17. 2026-06-24 14:05 UTCEPSS rescore
  18. 2026-06-23 21:33 UTCEPSS rescore
  19. 2026-06-23 21:33 UTCEPSS rescore
  20. 2026-06-22 14:25 UTCEPSS rescore
  21. 2026-06-22 14:25 UTCEPSS rescore
  22. 2026-06-21 14:56 UTCEPSS rescore
  23. 2026-06-21 14:56 UTCEPSS rescore
  24. 2026-06-21 01:59 UTCEPSS rescore
  25. 2026-06-19 19:25 UTCEPSS rescore
  26. 2026-06-19 19:25 UTCEPSS rescore
  27. 2026-06-18 17:52 UTCEPSS rescore
  28. 2026-06-18 17:52 UTCEPSS rescore
  29. 2026-06-17 17:53 UTCEPSS rescore
  30. 2026-06-16 17:52 UTCEPSS rescore
  31. 2026-06-15 17:49 UTCEPSS rescore
  32. 2026-06-14 23:18 UTCEPSS rescore
  33. 2026-06-14 21:45 UTCVendor advisory
  34. 2026-06-14 21:45 UTCGHSA enrichment
  35. 2026-06-14 09:18 UTCVendor advisory
  36. 2026-06-14 09:18 UTCGHSA enrichment
  37. 2026-06-13 23:00 UTCEPSS rescore
  38. 2026-06-12 23:12 UTCEPSS rescore
  39. 2026-06-12 23:12 UTCEPSS rescore
  40. 2026-06-12 05:55 UTCVendor advisory
  41. 2026-06-12 05:55 UTCGHSA enrichment
  42. 2026-06-11 17:28 UTCVendor advisory
  43. 2026-06-11 17:28 UTCGHSA enrichment
  44. 2026-06-11 14:00 UTCEPSS rescore
  45. 2026-06-11 04:58 UTCVendor advisory
  46. 2026-06-11 04:58 UTCGHSA enrichment
  47. 2026-06-10 22:18 UTCEPSS rescore
  48. 2026-06-10 13:22 UTCEPSS rescore
  49. 2026-06-10 13:07 UTCVendor advisory
  50. 2026-06-10 13:07 UTCGHSA enrichment
  51. 2026-06-10 00:40 UTCVendor advisory
  52. 2026-06-10 00:40 UTCGHSA enrichment
  53. 2026-06-09 12:13 UTCVendor advisory
  54. 2026-06-09 12:13 UTCGHSA enrichment
  55. 2026-06-08 23:46 UTCGHSA enrichment
  56. 2026-06-08 23:45 UTCGHSA enrichment
  57. 2026-06-08 14:17 UTCEPSS rescore
  58. 2026-06-08 14:17 UTCEPSS rescore
  59. 2026-06-08 04:48 UTCGHSA enrichment
  60. 2026-06-07 16:22 UTCGHSA enrichment
  61. 2026-06-07 15:25 UTCEPSS rescore
  62. 2026-06-07 15:25 UTCEPSS rescore
  63. 2026-06-07 15:25 UTCEPSS rescore
  64. 2026-06-07 03:55 UTCGHSA enrichment
  65. 2026-06-06 15:28 UTCGHSA enrichment
  66. 2026-06-06 13:47 UTCEPSS rescore
  67. 2026-06-06 13:47 UTCEPSS rescore
  68. 2026-06-06 02:53 UTCGHSA enrichment
  69. 2026-06-05 22:47 UTCEPSS rescore
  70. 2026-06-05 22:47 UTCEPSS rescore
  71. 2026-06-05 14:20 UTCGHSA enrichment
  72. 2026-06-05 01:53 UTCGHSA enrichment
  73. 2026-06-04 13:26 UTCGHSA enrichment
  74. 2026-06-04 13:12 UTCEPSS rescore
  75. 2026-06-04 13:12 UTCEPSS rescore

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Frequently asked(5)

What is CVE-2026-31786?
CVE-2026-31786 is a high vulnerability published on April 30, 2026. In the Linux kernel, the following vulnerability has been resolved: Buffer overflow in drivers/xen/sys-hypervisor.c The build id returned by HYPERVISORxenversion(XENVERbuildid) is neither NUL terminated nor a string. The first causes a buffer overflow as sprintf in buildid_show will read and copy…
When was CVE-2026-31786 disclosed?
CVE-2026-31786 was first published in the National Vulnerability Database on April 30, 2026, with the most recent update on June 14, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-31786 actively exploited?
CVE-2026-31786 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 9.7% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-31786?
CVE-2026-31786 has a CVSS v4.0 base score of 7.8 (CNA self-assessment; NVD's own analysis pending).
How do I remediate CVE-2026-31786?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-31786, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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