{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0"
              },
              {
                "fixed": "5.5.1"
              },
              {
                "introduced": "4.6.0"
              },
              {
                "fixed": "5.5.0"
              }
            ],
            "source": [
              "AFFECTED_FIELD",
              "DESCRIPTION"
            ]
          },
          "events": [
            {
              "introduced": "d2ed0f7810e4f05a2fc6348286b622abf6464751"
            },
            {
              "fixed": "be0b989473ec2b929f581234505aed487cbaa5a1"
            }
          ],
          "repo": "https://github.com/vrana/adminer",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-fr74-9mf9-gf44"
  ],
  "database_specific": {
    "cna_assigner": "VulnCheck",
    "cwe_ids": [
      "CWE-20"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/16xxx/CVE-2026-16434.json"
  },
  "details": "Adminer 4.6.0 through 5.5.0 (fixed in 5.5.1) contains an incomplete fix for a prior X-Forwarded-Prefix vulnerability (GHSA-8478-xrj3-h9c2). The validation guard (bootstrap.inc.php) only rejects prefixes matching ^/[^/], blocking //evil.com but allowing values such as /\\evil.com whose second character is a backslash. Because browsers normalize backslash to forward slash, a network-path reference survives into REQUEST_URI and reaches cookie_path(), affecting the Set-Cookie Path attribute. Exploitation requires that clients can set the X-Forwarded-Prefix header (a misconfigured or absent reverse proxy). Impact is limited to anomalous cookie-path scoping.",
  "id": "CVE-2026-16434",
  "modified": "2026-08-28T03:30:32.792270004Z",
  "published": "2026-08-25T01:29:57.018Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/16xxx/CVE-2026-16434.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/vrana/adminer/security/advisories/GHSA-fr74-9mf9-gf44"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-16434"
    },
    {
      "type": "ADVISORY",
      "url": "https://www.vulncheck.com/advisories/adminer-before-x-forwarded-prefix-backslash-bypass"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Adminer before 5.5.1 X-Forwarded-Prefix Backslash Bypass"
}