Threats / Notepad++ / CVE-2025-15556
CVE-2025-15556
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-08-04
Notepad++ vulnerability
Notepad++ WinGUp updater downloads code without integrity verification, allowing attackers to intercept updates and execute arbitrary code with user privileges.
Verdict
Today item — known-exploited.
An attacker positioned to intercept or redirect update traffic can deliver malicious installers during Notepad++ updates, achieving arbitrary code execution. The vulnerability stems from missing cryptographic integrity checks on downloaded update packages.
CISA KEV Yes · 2026-02-125EPSS 0.01268 (verify live)6CVSS 7.73CISA SSVC Exploitation: active · Automatable: no · Impact: total4
01
Is it exploitable?
— the evidence, ranked above the scoreReported exploitation
6 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2026-02-12).
Probability (EPSS)
EPSS 0.01268 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
CVSS 7.7 (CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N) · Affected: Notepad++, Notepad++. Confirm exact fixed builds in the vendor advisory.CVSS — CNA-assigned (CVE.org), version 4.0, set at disclosure.
Weakness (CWE)
Mapped to CWE-494 Download Without Integrity Check — weakness family: Path traversal / file.CWE — CNA-assigned (CVE.org); the weakness class drives how the flaw is exploited.
CISA SSVC (triage disposition)
Exploitation: active · Automatable: no · Technical Impact: totalCISA's own stakeholder-specific triage inputs, published in the CVE record (CISA Coordinator role). NOTE: this is CISA's three decision points; the final Act/Attend/Track decision also requires a Mission & Well-being input not published here, so no overall decision is asserted.
Currency of the record
CISA added this to its KEV catalog 9 days after the CVE record was published.KEV lag = CISA-KEV dateAdded − CVE.org datePublished; a floor on how long the known-exploited flaw sat in the public record before the federal catalog listed it. Severity/weakness here is CNA- or CISA-assigned (current at disclosure), independent of NVD's analysis backlog.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
I intercept or redirect the update request to my controlled server.
Business
Update infrastructure becomes a pivot point for endpoint compromise.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I serve a malicious installer that appears legitimate to the WinGUp updater.
Business
User systems execute attacker code with the privileges of the logged-in user.
3
Lateral reach — past segmentation narrative 3
Attacker
I establish persistence or lateral movement from the compromised endpoint.
Business
Widespread client-side compromise across organizations using Notepad++ for development or administration.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05