{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "4.0.0-beta.1"
              },
              {
                "fixed": "4.0.5"
              },
              {
                "introduced": "0"
              },
              {
                "fixed": "3.2.12"
              }
            ],
            "source": "AFFECTED_FIELD"
          },
          "events": [
            {
              "introduced": "c2932f06fe41f11e723879f8febf3e96b91d5750"
            },
            {
              "fixed": "3cb0ee7fbc01f8d3e84eaddf55350aced2dd4bfc"
            },
            {
              "introduced": "0"
            },
            {
              "fixed": "28579da80af507294dbdf9ae5b44ad9c185d0720"
            }
          ],
          "repo": "https://github.com/yafnet/yafnet",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-33gv-fc78-qgf5"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-116",
      "CWE-79",
      "CWE-80"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/43xxx/CVE-2026-43938.json"
  },
  "details": "YetAnotherForum.NET (YAF.NET) is a C# ASP.NET forum. Prior to 4.0.5 and 3.2.12, the application's database logger (YAFNET.Core/Logger/DbLogger.cs) captures the incoming request's User-Agent header into a JObject, serializes it with JsonConvert, and stores the result in the EventLog.Description column whenever an event (e.g., an unhandled exception) is logged. The admin event-log page (YetAnotherForum.NET/Pages/Admin/EventLog.cshtml.cs) later deserializes that JSON in FormatStackTrace() and interpolates the UserAgent value directly into an HTML string with no encoding, and the Razor view EventLog.cshtml emits the result through @Html.Raw. This vulnerability is fixed in 4.0.5 and 3.2.12.",
  "id": "CVE-2026-43938",
  "modified": "2026-07-08T05:38:49.742899728Z",
  "published": "2026-05-12T13:57:56.951Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/43xxx/CVE-2026-43938.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/YAFNET/YAFNET/security/advisories/GHSA-33gv-fc78-qgf5"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-43938"
    }
  ],
  "schema_version": "1.7.5",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "YAF.NET: Unauthenticated Stored Second-Order XSS in Admin Event Log via Reflected `User-Agent` Header"
}