CVE-2025-66620
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 · uneditedAn unused webshell in MicroServer allows unlimited login attempts, with sudo rights on certain files and directories. An attacker with admin access to MicroServer can gain limited shell access, enabling persistence through reverse shells, and the ability to modify or remove data stored in the file system.
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 confidenceAn unused/default webshell in MicroServer allows unlimited login attempts and provides sudo rights on certain files and directories. An attacker with admin-level access to MicroServer can exploit this webshell to gain limited shell access, establish persistence via reverse shells, and modify or delete filesystem data.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data< MS_4.1_14142CVSS 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
- Low
- Privileges
- High
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
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.
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Check firmware versionAccess the MicroServer admin interface or check system information to identify the installed firmware version. Look for a version string like MS_X.X_XXXXX in the system settings or about page.Affected if The firmware version is lower than MS_4.1_14142 (e.g., MS_4.0_XXXXX or earlier)
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Identify unused or default webshellReview the MicroServer web configuration files and directories for any unused, default, or hidden webshell scripts. Check for unexpected CGI, PHP, or shell script files in the web root or admin directories.Affected if An unused or default webshell is present on the system that is not actively used for legitimate administration
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Verify login attempt restrictionsTest the login interface by attempting multiple failed login attempts. Check if there is any account lockout policy, rate limiting, or captcha enforced after repeated failures.Affected if The system allows unlimited login attempts without any lockout, rate limiting, or captcha controls
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Review sudo permissionsExamine the sudoers configuration or equivalent permission settings on the MicroServer. Look for sudo entries that grant elevated permissions on files and directories.Affected if The configuration grants sudo rights to unnecessary files or directories beyond what is required for normal administration
A user is affected if their MicroServer firmware version is below MS_4.1_14142 and contains an unused webshell with unrestricted login and elevated sudo permissions.
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 · scopedRemove or disable the unused webshell, implement account lockout policies/rate limiting on login attempts, and restrict sudo permissions to only necessary commands and files.
MS_4.1_14142
- 1. Identify all Weather Microserver devices in the environment running firmware versions prior to MS_4.1_14142
- 2. Schedule a maintenance window for firmware update to minimize operational impact
- 3. Obtain the firmware update from the official vendor distribution channel
- 4. Upload and apply the MS_4.1_14142 firmware update to each affected MicroServer device
- 5. After updating, verify the webshell has been removed by checking for the absence of the unused/backdoor script
- 6. Confirm the device is functioning normally post-update
- 7. Review admin access logs to check for any signs of exploitation prior to the update
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation3.0 h
- Implementation6.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,984.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2025-66620 — 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-2025-66620 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
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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