Vulnerability in Notepad (CVE-2026-52885)
Summary
Vulnerability in Notepad (CVE-2026-52885). Data can be tampered with by attackers. Mitigation: upgrade to 8.9.6.4 or later.
Original description
The description as published by the source.
Notepad++ is a free and open-source source code editor. Prior to 8.9.6.4, NppCommands.cpp checks the HMAC of the on-disk shortcuts.xml at the moment a user command fires (Time-of-Check). However, the command payload is taken from the in-memory _userCommands vector, which is populated at application startup and never re-synchronized with the on-disk file (Time-of-Use). Swapping shortcuts.xml between startup and command execution causes the HMAC check to validate a clean file while a malicious command runs. An attacker with write access to shortcuts.xml places a malicious version on disk before launch, then immediately restores the legitimate file. The HMAC check at execution time validates the restored legitimate file (check passes), while the malicious payload executes from memory. This vulnerability is fixed in 8.9.6.4.
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-2026-52885 has been found in Notepad.
Data can be tampered with by attackers. CVSS score: 6.3/10.
What to do: upgrade Notepad to 8.9.6.4 or later.
If unsure, ask your IT team or search "Notepad CVE-2026-52885" on the vendor's site.
CVE-2026-52885 (Notepad) — CWE-367 / CVSS v3 6.3
Attack vector: local / no user interaction
Patched: 8.9.6.4 — 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-367) exists in Notepad.
Check the vendor advisory for the affected versions of Notepad.
Severity: Medium (CVSS 6.3/10). Data can be tampered with by attackers.
Update to 8.9.6.4.
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 8.9.6.4ステージング環境で 8.9.6.4 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
- advisory github.com
- advisory github.com
- advisory nvd.nist.gov
- patch github.com