{"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-2026-43939 exists.","fix":"Upgrade YAFNET.Core to a fixed version for your release line: 3.2.12 or 4.0.5.","what":"CVE-2026-43939 is a high-severity cross-site scripting vulnerability in YAFNET, published on 12 May 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link."},"fix_prompt":"Check this codebase for CVE-2026-43939 and fix it if it is affected.\n\nWhat it is: CVE-2026-43939 is a high-severity cross-site scripting vulnerability in YAFNET, published on 12 May 2026. Any signed-in user can exploit it over the network, 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-2026-43939 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-2026-43939/ (Markdown: https://insights.sbomify.com/CVE-2026-43939/index.md)","id":"CVE-2026-43939","markdown":"https://insights.sbomify.com/CVE-2026-43939/index.md","name":"CVE-2026-43939","record":{"aliases":["GHSA-8rq5-wwpp-fmj2"],"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 software","requires_auth":"low_privilege","summary":"Attackers can inject malicious JavaScript into forum posts, executing arbitrary code in the browsers of all users viewing the thread.","user_interaction":"required","vuln_class":"xss"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"GitHub_M","cpe":[],"cvss":{"score":7.3,"severity":"high","source":"cna","vector":"CVSS:3.1/AV:N/AC:L/PR:L/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 thread posting and reply feature accepts user-supplied content via a a post or reply that is stored server-side and later rendered back into the thread page without adequate HTML sanitization or contextual output encoding.  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: Stored XSS in Forum Thread Posts/Replies Allowing Arbitrary JavaScript Execution for All Thread Viewers","id":"CVE-2026-43939","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":"NuGet","product":null,"products":[],"type":"xss","year":"2026"},"n_packages":4,"n_references":1,"next":{"headline":"electerm: Path traversal in electerm runWidget leads to arbitrary code execution","id":"CVE-2026-43940"},"packages":[{"ecosystem":"NuGet","fixed":["3.2.12"],"introduced":["0"],"last_affected":[],"package":"YAFNET.Core","purl":null,"source":"GHSA-8rq5-wwpp-fmj2"},{"ecosystem":"NuGet","fixed":["3.2.12"],"introduced":["0"],"last_affected":[],"package":"YAFNET.Core","purl":"pkg:nuget/YAFNET.Core","source":"GHSA-8rq5-wwpp-fmj2"},{"ecosystem":"NuGet","fixed":["4.0.5"],"introduced":["4.0.0-beta01"],"last_affected":[],"package":"YAFNET.Core","purl":null,"source":"GHSA-8rq5-wwpp-fmj2"},{"ecosystem":"NuGet","fixed":["4.0.5"],"introduced":["4.0.0-beta01"],"last_affected":[],"package":"YAFNET.Core","purl":"pkg:nuget/YAFNET.Core","source":"GHSA-8rq5-wwpp-fmj2"}],"prev":{"headline":"YAF.NET: Unauthenticated Stored Second-Order XSS in Admin Event Log via Reflected `User-Agent` Header","id":"CVE-2026-43938"},"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":"2026-05-13","vendors":["YAFNET"]},"summary":"Attackers can inject malicious JavaScript into forum posts, executing arbitrary code in the browsers of all users viewing the thread.","url":"https://insights.sbomify.com/CVE-2026-43939/"}