CVE-2026-39834

CRITICALNVD 9.19.1—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.1 under NVD CVSS v3. EPSS exploit probability: 0.5%, top 63% 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: epss, nvd
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.

When writing data larger than 4GB in a single Write call on an SSH channel, an integer overflow in the internal payload size calculation caused the write loop to spin indefinitely, sending empty packets without making progress. The size comparison now uses int64 to prevent truncation.

CVSS v3
9.1
EG Score
9.1(medium)
EPSS
37.4%
KEV
Not listed

Published

May 22, 2026

Last Modified

May 28, 2026

Advisory Details (4)

Auto-updated May 28, 2026
No patch confirmed yet.
generic

GO-2026-5020 - Go Packages

https://pkg.go.dev/vuln/GO-2026-5020
generic
https://groups.google.com/g/golang-announce/c/a082jnz-LvI
generic

x/crypto/ssh: infinite loop on large channel writes · Issue #79567 · golang/go · GitHub

https://go.dev/issue/79567
generic
https://go.dev/cl/781663

Vendor Advisories for CVE-2026-39834(3)

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
ubuntulxd-tools (2.0.11-0ubuntu1~16.04.4+esm3) @ xenial2026-06-29ubuntu
ubuntugoogle-guest-agent (20240716.00-0ubuntu1~16.04.0+esm3) @ xenial2026-06-29ubuntu

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.

Additional Vendor Advisories

(2)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 9× in last 7d / 79× 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 296 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 20:38 UTCEG score recompute
  21. 2026-06-29 20:38 UTCVendor advisory
  22. 2026-06-29 16:40 UTCEG score recompute
  23. 2026-06-29 16:40 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 11:53 UTCEG score recompute
  2. 2026-06-28 11:53 UTCVendor advisory
  3. 2026-06-28 07:50 UTCEG score recompute
  4. 2026-06-28 07:50 UTCVendor advisory
  5. 2026-06-28 04:56 UTCEPSS rescore
  6. 2026-06-28 03:28 UTCEG score recompute
  7. 2026-06-28 03:28 UTCVendor advisory
  8. 2026-06-27 23:30 UTCEG score recompute
  9. 2026-06-27 23:30 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 23:18 UTCEG score recompute
  18. 2026-06-26 23:18 UTCVendor advisory
  19. 2026-06-26 19:14 UTCEG score recompute
  20. 2026-06-26 19:14 UTCVendor advisory
  21. 2026-06-26 03:18 UTCEG score recompute
  22. 2026-06-26 03:18 UTCVendor advisory
  23. 2026-06-25 23:15 UTCEG score recompute
  24. 2026-06-25 23:15 UTCVendor advisory
  25. 2026-06-25 18:20 UTCEG score recompute
  26. 2026-06-25 18:20 UTCVendor advisory
  27. 2026-06-25 14:09 UTCEG score recompute
  28. 2026-06-25 14:09 UTCVendor advisory
  29. 2026-06-25 13:49 UTCEPSS rescore
  30. 2026-06-25 13:49 UTCEPSS rescore
  31. 2026-06-24 14:05 UTCEPSS rescore
  32. 2026-06-23 21:33 UTCEPSS rescore
  33. 2026-06-22 14:25 UTCEPSS rescore
  34. 2026-06-22 14:25 UTCEPSS rescore
  35. 2026-06-21 14:56 UTCEPSS rescore
  36. 2026-06-21 14:56 UTCEPSS rescore
  37. 2026-06-21 01:59 UTCEPSS rescore
  38. 2026-06-19 19:25 UTCEPSS rescore
  39. 2026-06-18 17:52 UTCEPSS rescore
  40. 2026-06-18 17:52 UTCEPSS rescore
  41. 2026-06-18 03:52 UTCEG score recompute
  42. 2026-06-18 03:52 UTCVendor advisory
  43. 2026-06-17 23:54 UTCEG score recompute
  44. 2026-06-17 19:56 UTCEG score recompute
  45. 2026-06-17 19:56 UTCVendor advisory
  46. 2026-06-17 17:53 UTCEPSS rescore
  47. 2026-06-17 14:55 UTCEG score recompute
  48. 2026-06-17 10:58 UTCEG score recompute
  49. 2026-06-17 03:24 UTCEG score recompute
  50. 2026-06-16 23:26 UTCEG score recompute
  51. 2026-06-16 23:26 UTCVendor advisory
  52. 2026-06-16 19:28 UTCEG score recompute
  53. 2026-06-16 19:28 UTCVendor advisory
  54. 2026-06-16 17:52 UTCEPSS rescore
  55. 2026-06-16 10:42 UTCEG score recompute
  56. 2026-06-16 10:42 UTCVendor advisory
  57. 2026-06-16 06:42 UTCEG score recompute
  58. 2026-06-16 06:42 UTCVendor advisory
  59. 2026-06-16 02:45 UTCEG score recompute
  60. 2026-06-16 02:45 UTCVendor advisory
  61. 2026-06-15 22:45 UTCEG score recompute
  62. 2026-06-15 22:45 UTCVendor advisory
  63. 2026-06-15 17:49 UTCEPSS rescore
  64. 2026-06-15 14:58 UTCEG score recompute
  65. 2026-06-15 14:58 UTCVendor advisory
  66. 2026-06-15 06:19 UTCEG score recompute
  67. 2026-06-15 06:19 UTCVendor advisory
  68. 2026-06-15 02:17 UTCEG score recompute
  69. 2026-06-15 02:17 UTCVendor advisory
  70. 2026-06-14 23:18 UTCEPSS rescore
  71. 2026-06-14 22:18 UTCEG score recompute
  72. 2026-06-14 22:18 UTCVendor advisory
  73. 2026-06-14 18:21 UTCEG score recompute
  74. 2026-06-14 18:21 UTCVendor advisory
  75. 2026-06-14 14:04 UTCEG score recompute

Frequently asked(5)

What is CVE-2026-39834?
CVE-2026-39834 is a critical vulnerability published on May 22, 2026. When writing data larger than 4GB in a single Write call on an SSH channel, an integer overflow in the internal payload size calculation caused the write loop to spin indefinitely, sending empty packets without making progress. The size comparison now uses int64 to prevent truncation.
When was CVE-2026-39834 disclosed?
CVE-2026-39834 was first published in the National Vulnerability Database on May 22, 2026, with the most recent update on May 28, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-39834 actively exploited?
CVE-2026-39834 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 37.4% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-39834?
CVE-2026-39834 has a CVSS v3 base score of 9.1 (NVD).
How do I remediate CVE-2026-39834?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-39834, 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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