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Medium

russh server userauth state is not reset when authentication principal changes

Type: advisorySources: OSV

Russh is a Rust SSH client & server library. From version 0.34.0-beta.1 to before version 0.61.0, the russh server authentication path keeps internal userauth state across SSH_MSG_USERAUTH_REQUEST messages without separating that state when the request principal changes. RFC 4252 allows the user name and service name fields to change between authentication requests. The issue is not that such changes are invalid. The issue is that russh-owned authentication state, such as remaining methods, partial-success state, and in-progress method state, can remain associated with the connection and then influence a later request for a different (user, service). This is an internal library state mismatch. This issue has been patched in version 0.61.0.

Products
Not specified
Affected versions
Not specified
Fixed versions
Not specified
CVEs
CVE-2026-46705
Confirmed fixed CVEs
Not specified
Updated in this feed
4 Nov 2026, 18:31 UTC · Revision 1

Source evidence

russh server userauth state is not reset when authentication principal changes

core-osv · Original source

Published 10 Jun 2026, 20:21 UTC

Russh is a Rust SSH client & server library. From version 0.34.0-beta.1 to before version 0.61.0, the russh server authentication path keeps internal userauth state across SSH_MSG_USERAUTH_REQUEST messages without separating that state when the request principal changes. RFC 4252 allows the user name and service name fields to change between authentication requests. The issue is not that such changes are invalid. The issue is that russh-owned authentication state, such as remaining methods, partial-success state, and in-progress method state, can remain associated with the connection and then influence a later request for a different (user, service). This is an internal library state mismatch. This issue has been patched in version 0.61.0.

osv:CVE-2026-46705
Complete source record
{
  "id": "0761cd77dfb84467a0874e82e22335b009e49120514a32ec74a231c7a5a43e0d",
  "url": "https://osv.dev/vulnerability/CVE-2026-46705",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "russh server userauth state is not reset when authentication principal changes",
    "summary": "Russh is a Rust SSH client & server library. From version 0.34.0-beta.1 to before version 0.61.0, the russh server authentication path keeps internal userauth state across SSH_MSG_USERAUTH_REQUEST messages without separating that state when the request principal changes. RFC 4252 allows the user name and service name fields to change between authentication requests. The issue is not that such changes are invalid. The issue is that russh-owned authentication state, such as remaining methods, partial-success state, and in-progress method state, can remain associated with the connection and then influence a later request for a different (user, service). This is an internal library state mismatch. This issue has been patched in version 0.61.0.",
    "evidence": "osv:CVE-2026-46705",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-46705",
      "aliases": [
        "CVE-2026-46705",
        "GHSA-hpv4-5h6f-wqr3"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/eugeny/russh",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "1947d6b1bb3a9d79840b5adf7eb9b33df2c6e4a7"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0.34.0-beta.1"
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                      {
                        "fixed": "0.61.0"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "0.61.0"
                      }
                    ],
                    "source": "DESCRIPTION"
                  }
                ]
              }
            }
          ],
          "versions": [
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            "v0.35.0-beta.2",
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          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-46705.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:38.152558715Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/46xxx/CVE-2026-46705.json",
        "https://github.com/Eugeny/russh/security/advisories/GHSA-hpv4-5h6f-wqr3",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-46705"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-287"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/46xxx/CVE-2026-46705.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-46705",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 505724,
  "published_at": "2026-06-10T20:21:35.177+00:00"
}