SSH servers parsing GSSAPI authentication requests do not validate the number of mechanisms specified in the request, allowing an attacker to cause unbounded memory consumption

{
  "id": "6ff2173ac2ff33b76e9aa8ce9e2b7d54e76ddb518edb251c8443191f064a5b33",
  "url": "https://osv.dev/vulnerability/CLEANSTART-2026-CZ18029",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "SSH servers parsing GSSAPI authentication requests do not validate the number of mechanisms specified in the request, allowing an attacker to cause unbounded memory consumption",
    "summary": "Security vulnerability affects the tempo package. SSH servers parsing GSSAPI authentication requests do not validate the number of mechanisms specified in the request, allowing an attacker to cause unbounded memory consumption.",
    "evidence": "osv:CLEANSTART-2026-CZ18029",
    "products": [
      {
        "name": {
          "value": "tempo",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "3.0.3-r4",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "CLEANSTART-2026-CZ18029",
      "aliases": [
        "CLEANSTART-2026-CZ18029"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "3.0.3-r4"
                }
              ]
            }
          ],
          "package": {
            "name": "tempo",
            "purl": "pkg:apk/cleanstart/tempo",
            "ecosystem": "CleanStart"
          },
          "database_specific": {
            "source": "https://github.com/cleanstart-dev/cleanstart-security-advisories/blob/main/advisories/2026/CLEANSTART-2026-CZ18029.json"
          }
        }
      ],
      "modified": "2026-10-21T01:15:05.806095699Z",
      "provider": "osv",
      "upstream": [
        "CVE-2025-58181"
      ],
      "references": [
        "https://github.com/cleanstart-dev/cleanstart-security-advisories/tree/main/advisories/2026/CLEANSTART-2026-CZ18029.json",
        "https://osv.dev/vulnerability/CVE-2025-58181",
        "https://nvd.nist.gov/vuln/detail/CVE-2025-58181"
      ],
      "provider_metadata": {}
    },
    "related_cves": [
      {
        "value": "CVE-2025-58181",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 390766,
  "published_at": "2026-10-20T00:39:11.82994+00:00"
}