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Critical

Invoking infinite loop on large channel writes in golang.org/x/crypto/ssh

Type: advisorySources: OSV

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.

Products
Not specified
Affected versions
Not specified
Fixed versions
Not specified
CVEs
CVE-2026-39834
Confirmed fixed CVEs
Not specified
Updated in this feed
7 Nov 2026, 18:13 UTC · Revision 1

Source evidence

Invoking infinite loop on large channel writes in golang.org/x/crypto/ssh

core-osv · Original source

Published 22 May 2026, 02:31 UTC

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.

osv:CVE-2026-39834
Complete source record
{
  "id": "1bb88bd5c16436ad1c4819522b43497b0a7f5a5ac1326fcfedd198e04da75399",
  "url": "https://osv.dev/vulnerability/CVE-2026-39834",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Invoking infinite loop on large channel writes in golang.org/x/crypto/ssh",
    "summary": "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.",
    "evidence": "osv:CVE-2026-39834",
    "products": [],
    "severity": "critical",
    "structured": {
      "id": "CVE-2026-39834",
      "aliases": [
        "CVE-2026-39834",
        "GHSA-rm3j-f69w-wqmq",
        "GO-2026-5020"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/golang/crypto",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "a1c0d9929856c8aba2b31f079340f00578eda803"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:golang:crypto:*:*:*:*:*:go:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "0.52.0"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v0.51.0",
            "v0.50.0",
            "v0.49.0",
            "v0.48.0",
            "v0.47.0",
            "v0.46.0",
            "v0.45.0",
            "v0.44.0",
            "v0.43.0",
            "v0.42.0",
            "v0.41.0",
            "v0.40.0",
            "v0.39.0",
            "v0.38.0",
            "v0.37.0",
            "v0.36.0",
            "v0.35.0",
            "v0.34.0",
            "v0.33.0",
            "v0.32.0",
            "v0.31.0",
            "v0.30.0",
            "v0.29.0",
            "v0.28.0",
            "v0.27.0",
            "v0.26.0",
            "v0.25.0",
            "v0.24.0",
            "v0.23.0",
            "v0.22.0",
            "v0.21.0",
            "v0.20.0",
            "v0.19.0",
            "v0.18.0",
            "v0.17.0",
            "v0.16.0",
            "v0.15.0",
            "v0.14.0",
            "v0.13.0",
            "v0.12.0",
            "v0.11.0",
            "v0.10.0",
            "v0.9.0",
            "v0.8.0",
            "v0.7.0",
            "v0.6.0",
            "v0.5.0",
            "v0.4.0",
            "v0.3.0",
            "v0.2.0",
            "v0.1.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-39834.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:51.403832468Z",
      "provider": "osv",
      "references": [
        "https://go.dev/cl/781663",
        "https://go.dev/issue/79567",
        "https://groups.google.com/g/golang-announce/c/a082jnz-LvI",
        "https://pkg.go.dev",
        "https://pkg.go.dev/vuln/GO-2026-5020",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/39xxx/CVE-2026-39834.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-39834"
      ],
      "provider_metadata": {
        "cna_assigner": "Go",
        "unresolved_ranges": [
          {
            "extracted_events": [
              {
                "range": [
                  {
                    "fixed": "0.52.0"
                  }
                ],
                "source": "AFFECTED_FIELD",
                "strategy": "StandardRange"
              }
            ]
          }
        ],
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/39xxx/CVE-2026-39834.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-39834",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 520063,
  "published_at": "2026-05-22T02:31:27.54+00:00"
}