CVE-2026-31786

HIGHPre-NVD 7.87.8—
EchelonGraph scoreMEDIUM confidence

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

Triggered by: GitHub Security Advisory CVSS
Sources: cna:linux, epss, ghsa
7.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.8Exploit: None knownExposed: 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)
EG Risk
40(Track)
EG Risk 40/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity78% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
10%
KEV
Not listed

Published

April 30, 2026

Last Modified

August 5, 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(5)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatkernel-0:6.12.0-211.26.1.el10_22026-06-20redhat
redhatkernel-rt-0:4.18.0-553.134.1.rt7.475.el8_102026-06-16redhat
redhatkernel-0:4.18.0-553.134.1.el8_102026-06-16redhat
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.

Affected Packages

(5 across 4 ecosystems)
Debian:11(2)
PackageVulnerable rangeFixed inDependents
linux5.10.103-1 ... 5.10.92-2 (53 versions)5.10.257-1—
linux-6.16.1.106-3~deb11u1 ... 6.1.164-1~deb11u1 (16 versions)6.1.170-1~deb11u1—
Debian:12(1)
PackageVulnerable rangeFixed inDependents
linux6.1.106-1 ... 6.1.99-1 (48 versions)6.1.170-1—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
linux6.12.38-1 ... 6.12.85-1~bpo12+1 (17 versions)6.12.85-1—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
linux6.12.100-1 ... 7.0.1-1~exp1 (132 versions)7.0.3-1—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 5× in last 7d / 32× 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 241 total refreshes for this CVE.

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

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 August 5, 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 0% probability of exploitation in the next 30 days, which ranks it in the top 90.4% of all scored CVEs.
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.

Dependency Blast Radius

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