Out-of-Bounds Read in Notepad (CVE-2026-48770)
Summary
Vulnerability in Notepad (CVE-2026-48770). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 8.9.6.1 or later.
Original description
The description as published by the source.
Notepad++ is a free and open-source source code editor. Prior to 8.9.6.1, a local process in the same interactive Windows session can send a malformed WM_COPYDATA message to Notepad++ using the COPYDATA_FULL_CMDLINE path. The handler appears to process COPYDATASTRUCT.lpData as an unbounded NUL-terminated wchar_t* instead of enforcing COPYDATASTRUCT.cbData. This vulnerability is fixed in 8.9.6.1.
Source: NIST National Vulnerability Database NVD
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-2026-48770 has been found in Notepad.
Risk of unauthorized operations or information disclosure. CVSS score: 5.0/10.
What to do: upgrade Notepad to 8.9.6.1 or later.
If unsure, ask your IT team or search "Notepad CVE-2026-48770" on the vendor's site.
CVE-2026-48770 (Notepad) — CWE-125 / CVSS v3 5.0
Attack vector: local
Patched: 8.9.6.1 — 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.
Out-of-bounds read (CWE-125) exists in Notepad.
Check the vendor advisory for the affected versions of Notepad.
Severity: Medium (CVSS 5.0/10). Risk of unauthorized operations or information disclosure.
Update to 8.9.6.1.
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 'Notepad' . 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 'Notepad' . | 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
Notepad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 Notepad to 8.9.6.1ステージング環境で 8.9.6.1 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。
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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。
References
- exploit github.com
- patch security-advisories@github.com