{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "cpe": "cpe:2.3:a:gofiber:fiber:*:*:*:*:*:go:*:*",
            "extracted_events": [
              {
                "introduced": "0"
              },
              {
                "fixed": "2.52.12"
              },
              {
                "introduced": "3.0.0"
              },
              {
                "fixed": "3.1.0"
              }
            ],
            "source": "CPE_RANGE"
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "6cba19533db837ae5c9c0f5941dec5dae019e18c"
            },
            {
              "introduced": "f8f34f642fb3682c341ede7816e7cf861aa7df89"
            },
            {
              "fixed": "3c24ebefe5009e88f9f9258b472e8021160179bf"
            }
          ],
          "repo": "https://github.com/gofiber/fiber",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-qjv7-627w-8qjv"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-79"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42554.json"
  },
  "details": "Fiber is a web framework for Go. Prior to 2.52.12 and 3.1.0, Cross-Site Scripting vulnerability in Go Fiber allows a remote attacker to inject arbitrary HTML/JavaScript by supplying Accept: text/html on any request whose handler passes attacker-influenced data to the AutoFormat() feature. The developer opts into content negotiation by calling AutoFormat(), but does not opt into raw HTML emission for a particular request; Fiber chooses that branch from attacker-controlled Accept. The html branch is the sole outlier in a method whose name (AutoFormat) and symmetrical structure actively telegraph \"safe, format-agnostic reply.\" This vulnerability is fixed in 2.52.12 and 3.1.0.",
  "id": "CVE-2026-42554",
  "modified": "2026-07-15T01:49:07.771719071Z",
  "published": "2026-05-11T21:47:17.133Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42554.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/gofiber/fiber/security/advisories/GHSA-qjv7-627w-8qjv"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-42554"
    }
  ],
  "schema_version": "1.8.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Fiber: XSS in AutoFormat Content Negotiation"
}