Vulnerability-Lookup

FKIE_CVE-2026-39834

Vulnerability from fkie_nvd - Published: 2026-05-22 04:16 - Updated: 2026-05-22 04:16

Severity

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.

References

	URL	Tags
	security@golang.org	https://go.dev/cl/781663
	security@golang.org	https://go.dev/issue/79567
	security@golang.org	https://groups.google.com/g/golang-announce/c/a082jnz-LvI
	security@golang.org	https://pkg.go.dev/vuln/GO-2026-5020

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "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."
    }
  ],
  "id": "CVE-2026-39834",
  "lastModified": "2026-05-22T04:16:24.237",
  "metrics": {},
  "published": "2026-05-22T04:16:24.237",
  "references": [
    {
      "source": "security@golang.org",
      "url": "https://go.dev/cl/781663"
    },
    {
      "source": "security@golang.org",
      "url": "https://go.dev/issue/79567"
    },
    {
      "source": "security@golang.org",
      "url": "https://groups.google.com/g/golang-announce/c/a082jnz-LvI"
    },
    {
      "source": "security@golang.org",
      "url": "https://pkg.go.dev/vuln/GO-2026-5020"
    }
  ],
  "sourceIdentifier": "security@golang.org",
  "vulnStatus": "Received"
}

CVE-2026-39834 (GCVE-0-2026-39834)

Vulnerability from cvelistv5 – Published: 2026-05-22 02:31 – Updated: 2026-05-22 18:50

Title

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

Summary

Severity

9.1 (Critical)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

CWE

CWE-190 - Integer Overflow or Wraparound

Assigner

References

4 references

URL	Tags
https://go.dev/issue/79567
https://groups.google.com/g/golang-announce/c/a08…
https://go.dev/cl/781663
https://pkg.go.dev/vuln/GO-2026-5020

Impacted products

1 product

Vendor	Product	Version
golang.org/x/crypto	golang.org/x/crypto/ssh	Affected: 0 , < 0.52.0 (semver)

Credits

NCC Group Cryptography Services, sponsored by Teleport

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "cvssV3_1": {
              "attackComplexity": "LOW",
              "attackVector": "NETWORK",
              "availabilityImpact": "HIGH",
              "baseScore": 9.1,
              "baseSeverity": "CRITICAL",
              "confidentialityImpact": "NONE",
              "integrityImpact": "HIGH",
              "privilegesRequired": "NONE",
              "scope": "UNCHANGED",
              "userInteraction": "NONE",
              "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H",
              "version": "3.1"
            }
          },
          {
            "other": {
              "content": {
                "id": "CVE-2026-39834",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-05-22T18:50:30.848292Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-05-22T18:50:51.339Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "collectionURL": "https://pkg.go.dev",
          "defaultStatus": "unaffected",
          "packageName": "golang.org/x/crypto/ssh",
          "product": "golang.org/x/crypto/ssh",
          "programRoutines": [
            {
              "name": "channel.WriteExtended"
            },
            {
              "name": "Dial"
            },
            {
              "name": "NewClientConn"
            },
            {
              "name": "NewServerConn"
            },
            {
              "name": "Session.CombinedOutput"
            },
            {
              "name": "Session.Output"
            },
            {
              "name": "Session.Run"
            },
            {
              "name": "Session.Shell"
            },
            {
              "name": "Session.Start"
            },
            {
              "name": "channel.Write"
            },
            {
              "name": "curve25519sha256.Client"
            },
            {
              "name": "curve25519sha256.Server"
            },
            {
              "name": "dhGEXSHA.Client"
            },
            {
              "name": "dhGEXSHA.Server"
            },
            {
              "name": "dhGroup.Client"
            },
            {
              "name": "dhGroup.Server"
            },
            {
              "name": "ecdh.Client"
            },
            {
              "name": "ecdh.Server"
            },
            {
              "name": "extChannel.Write"
            },
            {
              "name": "mlkem768WithCurve25519sha256.Client"
            },
            {
              "name": "mlkem768WithCurve25519sha256.Server"
            }
          ],
          "vendor": "golang.org/x/crypto",
          "versions": [
            {
              "lessThan": "0.52.0",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "value": "NCC Group Cryptography Services, sponsored by Teleport"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "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."
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "description": "CWE-190: Integer Overflow or Wraparound",
              "lang": "en"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-22T02:31:27.540Z",
        "orgId": "1bb62c36-49e3-4200-9d77-64a1400537cc",
        "shortName": "Go"
      },
      "references": [
        {
          "url": "https://go.dev/issue/79567"
        },
        {
          "url": "https://groups.google.com/g/golang-announce/c/a082jnz-LvI"
        },
        {
          "url": "https://go.dev/cl/781663"
        },
        {
          "url": "https://pkg.go.dev/vuln/GO-2026-5020"
        }
      ],
      "title": "Invoking  infinite loop on large channel writes in golang.org/x/crypto/ssh"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "1bb62c36-49e3-4200-9d77-64a1400537cc",
    "assignerShortName": "Go",
    "cveId": "CVE-2026-39834",
    "datePublished": "2026-05-22T02:31:27.540Z",
    "dateReserved": "2026-04-07T18:13:03.529Z",
    "dateUpdated": "2026-05-22T18:50:51.339Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

Action not permitted

FKIE_CVE-2026-39834

CVE-2026-39834 (GCVE-0-2026-39834)

Tags

Sightings

Nomenclature