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CVE-2026-43939
high
CVSS 7.3
Vulnerability in YAFNET.Core (CVE-2026-43939)
Summary
vulnerability in YAFNET.Core (CVE-2026-43939). Confidential information can be exposed externally. Exploitable via ``onerror``. Mitigation: upgrade to `3.2.12` or later.
AI summary snake-internal / snake-material-v2
A vulnerability tracked as **CVE-2026-43939** has been found in YAFNET.Core.
Attackers can target a specific entry point like ``onerror`` over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 7.3/10.
What to do: upgrade YAFNET.Core to **3.2.12** or later.
If unsure, ask your IT team or search "YAFNET.Core CVE-2026-43939" on the vendor's site.
CVE-2026-43939 (YAFNET.Core) — CWE-116 / CVSS v3 7.3
Attack vector: remote (network-reachable)
Attack surface: `onerror`
Patched: `3.2.12` — 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.
❓ What is the problem
**A vulnerability** (CWE-116) exists in YAFNET.Core. Attackers reach the vulnerable code path via ``onerror`` without authentication.
📍 Affected scope
YAFNET.Core — . Attack surface: `onerror`.
🔥 Severity
Severity: High (CVSS 7.3/10). Confidential information can be exposed externally
🔧 How to fix
Update to **3.2.12**.
🛡️ Workaround
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
🔍 Detection
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 (7 steps)
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。
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6Apply patch patch
Upgrade YAFNET.Core to 3.2.12ステージング環境で 3.2.12 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と、Step 3 で見つけた異常検知の続報チェックを含めること。
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7Post-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 Step 3 と同じログクエリでアラート再発が無いか継続監視。
Affected packages
nuget
YAFNET.Core
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.2.12"}]}]
References
- advisory https://nvd.nist.gov/vuln/detail/CVE-2026-43939
- package https://github.com/YAFNET/YAFNET
- web https://github.com/YAFNET/YAFNET/security/advisories/GHSA-8rq5-wwpp-fmj2
- web https://github.com/YAFNET/YAFNET/releases/tag/v3.2.12
- web https://github.com/YAFNET/YAFNET/releases/tag/v4.0.5
- web https://github.com/advisories/GHSA-8rq5-wwpp-fmj2