CVE-2026-52885 — Notepad++ TOCTOU: HMAC Checks Disk, Executes from Memory
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.
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- EPSS 0.1% (30-day exploitation probability)+0
- Technical severity (medium)+3
- CISA SSVC: exploitation "poc"+5
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
CISA SSVC assessment CISA
Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
- Documented patch — github.com (NIST National Vulnerability Database)
- Documented patch — github.com (NIST National Vulnerability Database)
First 24 hours
Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.
- Identify exposed assets running the affected vendor/product/version combinations (Notepad-plus-plus Notepad-plus-plus, Notepad-plus-plus Notepad++).
- Apply the fixed version or the patch documented under Remediation.
- Search available logs for exploit probes matching the vulnerability class (logic error), errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
| Vendor | Product | Versions | Status | Source |
|---|---|---|---|---|
| Notepad-plus-plus | Notepad-plus-plus | version < 8.9.6.4 | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Notepad-plus-plus | Notepad++ | < 8.9.6.4 | Vulnerable | NIST National Vulnerability Database |
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 7.5 | CVSS 4.0 | High | — | — | security-advisories@github.com via NIST National Vulnerability Database |
| 7.5 | CVSS 4.0 | High | — | — | GitHub_M via CVE Program (cve.org) e CISA ADP |
| 6.3 | CVSS 3.1 | Medium | 1.0 | 5.2 | nvd@nist.gov via NIST National Vulnerability Database |
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:H (score shown at the top: nvd@nist.gov) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
EPSS over time FIRST
Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 0.13%
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Local/physical vector: focus on endpoint telemetry (EDR) from affected hosts.
Timeline
What happened to this CVE, newest first.
- 2026
- Affected products added · notepad-plus-plus/notepad-plus-plus
- SSVC assessment updated
- Record published
- Fix documented
- CVSS changed · 6.3
- Source status changed · → Analyzed
- Record created in this database
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 1× Official description updated · Oct 13, 2026 – Oct 13, 2026
References
2 on the record
Elsewhere on this site
Related CVEs (same products)
- Medium CVE-2026-48770 Notepad++ WM_COPYDATA COPYDATA_FULL_CMDLINE local DoS crash Jun 26, 2026
- High CVE-2026-48778 Notepad++: Arbitrary Code Execution via config.xml commandLineInterpreter Jun 26, 2026
- High CVE-2026-48800 Notepad++: Arbitrary Code Execution via shortcuts.xml UserCommand Injection Jun 26, 2026
- High CVE-2026-52884 Notepad++: CVE-2026-48800 Bypass Jun 26, 2026
- High CVE-2026-46710 Notepad++: Privilege Escalation in the Installer via Uncontrolled Executable Search Path Jun 26, 2026
- Medium CVE-2026-6539 Notepad++ 8.9.3 Format String Injection via nativeLang.xml Apr 30, 2026
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record
Text assembled only from the fields above — no additional claims.
What should defenders know first?
CVE-2026-52885 is "Notepad++ TOCTOU: HMAC Checks Disk, Executes from Memory", rated Medium. It affects Notepad-plus-plus (Notepad-plus-plus); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 6.3 describes technical severity. EPSS 0.13% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.
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