Vulnerability in YAFNET.Core (CVE-2026-43937)
Summary
Vulnerability in YAFNET.Core (CVE-2026-43937). Successful exploitation can lead to full system takeover. Exploitable via PageSecurityCheckAttribute. Mitigation: upgrade to 4.0.5 or later.
Original description
The description as published by the source.
YetAnotherForum.NET (YAF.NET) is a C# ASP.NET forum. Prior to 4.0.5, Any admin OnPost… handler executes its side effects before the ResultFilterAttribute rewrites the response to a 302 to /Info/4. The most impactful abuse is /Admin/RunSql, whose OnPostRunQuery binds Editor from the POST body and passes it straight to IDbAccess.RunSql with no caller check, yielding arbitrary SQL execution for any low-privileged user. This vulnerability is fixed in 4.0.5.
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-43937 has been found in YAFNET.Core.
Attackers can target a specific entry point like PageSecurityCheckAttribute over the network to misuse the product.
Successful exploitation can lead to full system takeover. CVSS score: 8.8/10.
What to do: upgrade YAFNET.Core to 4.0.5 or later.
If unsure, ask your IT team or search "YAFNET.Core CVE-2026-43937" on the vendor's site.
CVE-2026-43937 (YAFNET.Core) — CWE-841 / CVSS v3 8.8
Attack vector: remote (network-reachable) / no user interaction
Attack surface: PageSecurityCheckAttribute / ResultFilterAttribute / OnPostRunQuery / Editor
Patched: 4.0.5 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-841) exists in YAFNET.Core. Attackers reach the vulnerable code path via PageSecurityCheckAttribute.
Check the vendor advisory for the affected versions of YAFNET.Core. Attack surface: PageSecurityCheckAttribute / ResultFilterAttribute / OnPostRunQuery / Editor.
Severity: High (CVSS 8.8/10). Successful exploitation can lead to full system takeover.
Update to 4.0.5.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'YAFNET.Core' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r 'YAFNET.Core' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
YAFNET.Coreを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade YAFNET.Core to 4.0.5ステージング環境で 4.0.5 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- advisory github.com
- advisory nvd.nist.gov
- advisory github.com
- package github.com
- web github.com
- web github.com
- web github.com