{"answers":{"affected":"4 open source packages ship an affected version, including YAFNET.Core.","exploited":"It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-43938 exists.","fix":"Upgrade YAFNET.Core to a fixed version for your release line: 3.2.12 or 4.0.5.","what":"CVE-2026-43938 is a high-severity cross-site scripting vulnerability in YAFNET, published on 12 May 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link."},"fix_prompt":"Check this codebase for CVE-2026-43938 and fix it if it is affected.\n\nWhat it is: CVE-2026-43938 is a high-severity cross-site scripting vulnerability in YAFNET, published on 12 May 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.\nExploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-43938 exists.\n\nAffected packages and fixed versions:\n- YAFNET.Core (NuGet): affected all versions; fixed in 3.2.12\n- YAFNET.Core (NuGet): affected all versions; fixed in 3.2.12\n- YAFNET.Core (NuGet): affected from 4.0.0-beta01; fixed in 4.0.5\n- YAFNET.Core (NuGet): affected from 4.0.0-beta01; fixed in 4.0.5\n\nTask:\n1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.\n2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.\n3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.\n4. Run the tests and summarise what changed and why.\n5. If nothing in the project is affected, say so and change nothing.\n\nReference: https://insights.sbomify.com/CVE-2026-43938/ (Markdown: https://insights.sbomify.com/CVE-2026-43938/index.md)","id":"CVE-2026-43938","markdown":"https://insights.sbomify.com/CVE-2026-43938/index.md","name":"CVE-2026-43938","record":{"aliases":["GHSA-33gv-fc78-qgf5"],"analysis":{"component_type":"web_application","fix_type":"upgrade","impacts":["code_execution","account_takeover"],"network_reachable":"yes","non_default_config":false,"product_category":"ASP.NET forum","requires_auth":"none","summary":"An attacker can inject malicious scripts into the admin event log via the User-Agent header, leading to stored XSS when viewed by administrators.","user_interaction":"required","vuln_class":"xss"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"GitHub_M","cpe":[],"cvss":{"score":8.1,"severity":"high","source":"cna","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N","version":"3.1"},"cwes":[{"id":"CWE-80","name":"Improper Neutralization of Script-Related HTML Tags in a Web Page"},{"id":"CWE-79","name":"Improper Neutralization of Input During Web Page Generation"},{"id":"CWE-116","name":"Improper Encoding or Escaping of Output"}],"description":"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.","ecosystems":["NuGet"],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"weaponised"},"has_fix":true,"headline":"YAF.NET: Unauthenticated Stored Second-Order XSS in Admin Event Log via Reflected `User-Agent` Header","id":"CVE-2026-43938","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":"NuGet","product":null,"products":[],"type":"xss","year":"2026"},"n_packages":4,"n_references":1,"next":{"headline":"YAF.NET: Stored XSS in Forum Thread Posts/Replies Allowing Arbitrary JavaScript Execution for All Thread Viewers","id":"CVE-2026-43939"},"packages":[{"ecosystem":"NuGet","fixed":["3.2.12"],"introduced":["0"],"last_affected":[],"package":"YAFNET.Core","purl":null,"source":"GHSA-33gv-fc78-qgf5"},{"ecosystem":"NuGet","fixed":["3.2.12"],"introduced":["0"],"last_affected":[],"package":"YAFNET.Core","purl":"pkg:nuget/YAFNET.Core","source":"GHSA-33gv-fc78-qgf5"},{"ecosystem":"NuGet","fixed":["4.0.5"],"introduced":["4.0.0-beta01"],"last_affected":[],"package":"YAFNET.Core","purl":null,"source":"GHSA-33gv-fc78-qgf5"},{"ecosystem":"NuGet","fixed":["4.0.5"],"introduced":["4.0.0-beta01"],"last_affected":[],"package":"YAFNET.Core","purl":"pkg:nuget/YAFNET.Core","source":"GHSA-33gv-fc78-qgf5"}],"prev":{"headline":"YAF.NET: Pre-Handler Authorization Bypass on Admin Pages Enabling Blind SQL Execution via `/Admin/RunSql`","id":"CVE-2026-43937"},"products":["YAFNET"],"published":"2026-05-12","related":[],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"CC BY 4.0","name":"GitHub Advisory Database","prefix":"GHSA"},{"class":"attribution","licence":"CWE Terms of Use","name":"CWE (MITRE)"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":"no","exploitation":"poc","technical_impact":"total"},"state":"PUBLISHED","updated":"2026-05-12","vendors":["YAFNET"]},"summary":"An attacker can inject malicious scripts into the admin event log via the User-Agent header, leading to stored XSS when viewed by administrators.","url":"https://insights.sbomify.com/CVE-2026-43938/"}