YAF.NET: Unauthenticated Stored Second-Order XSS in Admin Event Log via Reflected `User-Agent` Header
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- Fix
- Fixed in 4.0.5, 3.2.12
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: poc
- Automatable: no
- Technical impact: total
Summary
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.
Timeline
- CVE published
- CISA SSVC assessment
Exploitation: poc · Automatable: no · Technical impact: total
- Record last updated
Affected versions
- YAFNET YAFNET
From 4.0.0-beta.1 · fixed in 4.0.5; fixed in 3.2.12
- YAFNET.CoreNuGet
From 4.0.0-beta01 · fixed in 4.0.5
- YAFNET.CoreNuGet
fixed in 3.2.12