{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-43938", "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "state": "PUBLISHED", "assignerShortName": "GitHub_M", "dateReserved": "2026-05-04T16:59:09.089Z", "datePublished": "2026-05-12T13:57:56.951Z", "dateUpdated": "2026-05-12T15:39:46.446Z"}, "containers": {"cna": {"title": "YAF.NET: Unauthenticated Stored Second-Order XSS in Admin Event Log via Reflected `User-Agent` Header", "problemTypes": [{"descriptions": [{"cweId": "CWE-79", "lang": "en", "description": "CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')", "type": "CWE"}]}, {"descriptions": [{"cweId": "CWE-80", "lang": "en", "description": "CWE-80: Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS)", "type": "CWE"}]}, {"descriptions": [{"cweId": "CWE-116", "lang": "en", "description": "CWE-116: Improper Encoding or Escaping of Output", "type": "CWE"}]}], "metrics": [{"cvssV3_1": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 8.1, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N", "version": "3.1"}}], "references": [{"name": "https://github.com/YAFNET/YAFNET/security/advisories/GHSA-33gv-fc78-qgf5", "tags": ["x_refsource_CONFIRM"], "url": "https://github.com/YAFNET/YAFNET/security/advisories/GHSA-33gv-fc78-qgf5"}], "affected": [{"vendor": "YAFNET", "product": "YAFNET", "versions": [{"version": ">= 4.0.0-beta.1, < 4.0.5", "status": "affected"}, {"version": "< 3.2.12", "status": "affected"}]}], "providerMetadata": {"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "shortName": "GitHub_M", "dateUpdated": "2026-05-12T13:57:56.951Z"}, "descriptions": [{"lang": "en", "value": "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."}], "source": {"advisory": "GHSA-33gv-fc78-qgf5", "discovery": "UNKNOWN"}}, "adp": [{"references": [{"url": "https://github.com/YAFNET/YAFNET/security/advisories/GHSA-33gv-fc78-qgf5", "tags": ["exploit"]}], "metrics": [{"other": {"type": "ssvc", "content": {"timestamp": "2026-05-12T15:39:17.598324Z", "id": "CVE-2026-43938", "options": [{"Exploitation": "poc"}, {"Automatable": "no"}, {"Technical Impact": "total"}], "role": "CISA Coordinator", "version": "2.0.3"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-05-12T15:39:46.446Z"}}]}}

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