Pre-Authentication Remote Code Execution via `jato.clientSession` Deserialization in OpenAM

{
  "id": "2ff26caac782625967049de4831fc8e5b2a239794e2dac836a7cf639f834cb31",
  "url": "https://osv.dev/vulnerability/CVE-2026-33439",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Pre-Authentication Remote Code Execution via `jato.clientSession` Deserialization in OpenAM",
    "summary": "Open Access Management (OpenAM) is an access management solution. Prior to 16.0.6, OpenIdentityPlatform OpenAM is vulnerable to pre-authentication Remote Code Execution (RCE) via unsafe Java deserialization of the jato.clientSession HTTP parameter. This bypasses the WhitelistObjectInputStream mitigation that was applied to the jato.pageSession parameter after CVE-2021-35464. An unauthenticated attacker can achieve arbitrary command execution on the server by sending a crafted serialized Java object as the jato.clientSession GET/POST parameter to any JATO ViewBean endpoint whose JSP contains tags (e.g., the Password Reset pages). This vulnerability is fixed in 16.0.6.",
    "evidence": "osv:CVE-2026-33439",
    "products": [],
    "severity": "critical",
    "structured": {
      "id": "CVE-2026-33439",
      "aliases": [
        "CVE-2026-33439",
        "GHSA-2cqq-rpvq-g5qj"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/openidentityplatform/openam",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
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                {
                  "fixed": "4529f108e9f5d3b8f98b4afb3dd035a3c4d73a1b"
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              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "16.0.6"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "cpe": "cpe:2.3:a:openidentityplatform:openam:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "16.0.6"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
            "16.0.5",
            "16.0.4",
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          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-33439.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:32.736389584Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33439.json",
        "https://github.com/OpenIdentityPlatform/OpenAM/security/advisories/GHSA-2cqq-rpvq-g5qj",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-33439"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-502"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33439.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-33439",
        "evidence": "/id"
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    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 499998,
  "published_at": "2026-04-07T20:46:33.739+00:00"
}