CVE-2025-41255
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedCyberduck and Mountain Duck improperly handle TLS certificate pinning for untrusted certificates (e.g., self-signed), unnecessarily installing it to the Windows Certificate Store of the current user without any restrictions. This issue affects Cyberduck through 9.1.6 and Mountain Duck through 4.17.5.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · moderate confidenceCyberduck and Mountain Duck improperly handle TLS certificate pinning by accepting untrusted (self-signed) certificates and installing them to the Windows Certificate Store of the current user without any restrictions. This allows a man-in-the-middle attacker to inject malicious certificates into the user's certificate store, which then become trusted by other applications on the system.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- High
- Privileges
- None
- User interaction
- Required
- Scope
- Changed
- Confidentiality
- High
- Integrity
- High
- Availability
- None
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
-
Verify Cyberduck or Mountain Duck is installedCheck for the presence of Cyberduck or Mountain Duck installation directories, typically under C:\Program Files\Cyberduck or C:\Program Files\Mountain Duck. Also check the Windows registry under HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall for display names containing 'Cyberduck' or 'Mountain Duck'.Affected if Either Cyberduck or Mountain Duck is installed on the system.
-
Identify installed version of CyberduckOpen the Cyberduck application and navigate to Help > About, or right-click the Cyberduck.exe file in the installation directory, select Properties, and check the Details tab for the Version number.Affected if The installed version has not been patched and falls within the vulnerable version range.
-
Identify installed version of Mountain DuckOpen the Mountain Duck application and navigate to Help > About, or right-click the MountainDuck.exe file in the installation directory, select Properties, and check the Details tab for the Version number.Affected if The installed version has not been patched and falls within the vulnerable version range.
-
Inspect Windows Certificate Store for suspicious certificatesOpen certmgr.msc (Current User certificates) and review certificates in Personal, Trusted Root Certification Authorities, and Other People stores. Look for certificates recently added (check Issued On date) that correspond to servers the user connected to using Cyberduck or Mountain Duck, especially if those servers used self-signed certificates.Affected if New or unexpected certificates exist in the certificate store that were added during or after Cyberduck/Mountain Duck usage, particularly certificates from untrusted or unknown sources.
-
Review application logs for untrusted connection handlingLocate Cyberduck or Mountain Duck log files, typically found in %APPDATA%\Cyberduck\logs or %APPDATA%\Mountain Duck\logs. Search for entries indicating certificate acceptance or trust decisions.Affected if Logs show acceptance of self-signed or untrusted certificates during connections.
A user is affected if Cyberduck or Mountain Duck is installed with an unpatched version AND the user has connected to servers with untrusted certificates, resulting in certificates being added to the Windows Certificate Store.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scopedUpgrade to the latest versions of Cyberduck and Mountain Duck when patches become available. Avoid connecting to untrusted servers with self-signed certificates until the fix is applied.
Cyberduck: version 9.1.7 or later; Mountain Duck: version 4.17.6 or later
- 1. Identify the installed version of Cyberduck or Mountain Duck on the system
- 2. For Cyberduck: Navigate to the application and check Help > About to confirm the version
- 3. For Mountain Duck: Navigate to the application and check Help > About to confirm the version
- 4. If running Cyberduck version 9.1.6 or earlier, download and install the latest version from the official Cyberduck website
- 5. If running Mountain Duck version 4.17.5 or earlier, download and install the latest version from the official Mountain Duck website
- 6. Restart the application after upgrading
- 7. Verify the certificate pinning behavior no longer installs untrusted certificates to the Windows Certificate Store
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation4.0 h
- Implementation12.0 h
- Testing6.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $7,328.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2025-41255 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2025-41255 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
- No spam, self-promotion, credentials, or personal data