CVE-2026-39831

CRITICALPre-NVD 9.19.1—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.1 under CISA-ADP (Vulnrichment) CVSS v3.1 (NVD's own analysis pending). EPSS exploit probability: 0.4%, top 71% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: cisa-adp, epss
9.1
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 9.1Exploit: NoneExposed: 0

A fix is available — apply it.

The Verify() method for FIDO/U2F security key types ([email protected], [email protected]) did not check the User Presence flag. Signatures generated without physical touch were accepted, allowing unattended use of a hardware security key. To restore the previous behavior, return a "no-touch-required" extension in Permissions.Extensions from PublicKeyCallback.

CVSS v3
9.1
EG Score
9.1(medium)
EPSS
29.5%
KEV
Not listed

Published

May 22, 2026

Last Modified

June 2, 2026

Advisory Details (4)

Auto-updated Jun 1, 2026
No patch confirmed yet.
generic

GO-2026-5019 - Go Packages

https://pkg.go.dev/vuln/GO-2026-5019
generic
https://groups.google.com/g/golang-announce/c/a082jnz-LvI
generic

x/crypto/ssh: bypass of FIDO/U2F security keys physical interaction · Issue #79566 · golang/go · GitHub

https://go.dev/issue/79566
generic
https://go.dev/cl/781662

Vendor Advisories for CVE-2026-39831(6)

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

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntugoogle-guest-agent (20241011.01-0ubuntu1~18.04.0+esm3) @ bionic2026-06-29ubuntu

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

(1 across 1 ecosystem)
Go(1)
PackageVulnerable rangeFixed inDependents
golang.org/x/crypto—0.52.0—

Weakness Classification(1)

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

All Vendor Advisories

(1)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 9× in last 7d / 72× 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 195 total refreshes for this CVE.

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

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-39831?
CVE-2026-39831 is a critical vulnerability published on May 22, 2026. The Verify() method for FIDO/U2F security key types ([email protected], [email protected]) did not check the User Presence flag. Signatures generated without physical touch were accepted, allowing unattended use of a hardware security key. To restore the previous behavior,…
When was CVE-2026-39831 disclosed?
CVE-2026-39831 was first published in the National Vulnerability Database on May 22, 2026, with the most recent update on June 2, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-39831 actively exploited?
CVE-2026-39831 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 29.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-39831?
CVE-2026-39831 has a CVSS v3.1 base score of 9.1 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-39831?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-39831, 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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