CAT through 3.1.0 Session Cookie Forgery via Unkeyed hashCode Checksum

{
  "id": "2b4f72a9098f4759dbd4e36020e01dd2c739b54113319c28251c11fe3691b2a8",
  "url": "https://osv.dev/vulnerability/CVE-2026-85181",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CAT through 3.1.0 Session Cookie Forgery via Unkeyed hashCode Checksum",
    "summary": "CAT uses Java String.hashCode as the sole integrity check for session cookies without server-side keying, allowing attackers to forge valid checksums offline. Attackers can set the x-forwarded-for header to bypass IP binding validation and create admin sessions with full configuration access.",
    "evidence": "osv:CVE-2026-85181",
    "products": [],
    "severity": "critical",
    "structured": {
      "id": "CVE-2026-85181",
      "aliases": [
        "CVE-2026-85181"
      ],
      "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/dianping/cat",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "last_affected": "3152e71443eea268773aec1f492899bc0abd4d07"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "last_affected": "3.1.0"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  }
                ]
              }
            }
          ],
          "versions": [
            "3.1.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-85181.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:24.228027852Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/85xxx/CVE-2026-85181.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-85181",
        "https://www.vulncheck.com/advisories/cat-through-3.1.0-session-cookie-forgery-via-unkeyed-hashcode-checksum",
        "https://github.com/dianping/cat/issues/2384",
        "https://github.com/dianping/cat",
        "https://github.com/dianping/cat/blob/3.1.0/cat-home/src/main/java/com/dianping/cat/system/page/login/service/TokenBuilder.java",
        "https://github.com/dianping/cat/blob/3.1.0/cat-home/src/main/java/com/dianping/cat/util/HttpUtils.java"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-565"
        ],
        "cna_assigner": "VulnCheck",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/85xxx/CVE-2026-85181.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-85181",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 490565,
  "published_at": "2026-09-03T14:12:19.751+00:00"
}