CVE-2021-27856
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 · uneditedFatPipe WARP, IPVPN, and MPVPN software prior to versions 10.1.2r60p91 and 10.2.2r42 includes an account named "cmuser" that has administrative privileges and no password. Older versions of FatPipe software may also be vulnerable. The FatPipe advisory identifier for this vulnerability is FPSA002.
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 · high confidenceFatPipe WARP, IPVPN, and MPVPN software versions prior to 10.1.2r60p91 and 10.2.2r42 contain an undocumented administrative account named 'cmuser' that is configured with full administrative privileges but has no password set, allowing unauthenticated remote attackers to gain complete administrative access to the affected device.
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= 5.2.0= 6.1.2= 7.1.2= 9.1.2= 10.1.2= 10.2.2= 5.2.0= 6.1.2= 7.1.2= 9.1.2= 10.1.2= 10.2.2= 5.2.0= 6.1.2= 7.1.2= 9.1.2= 10.1.2= 10.2.2CVSS 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
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/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.
-
Identify the installed FatPipe firmware versionAccess the device web interface and navigate to the About or System Information page, or use the CLI command 'version' or 'show system-info' to retrieve the firmware version numberAffected if The installed version matches 5.2.0, 6.1.2, 7.1.2, 9.1.2, 10.1.2, or 10.2.2, or is any version prior to 10.1.2r60p91 or 10.2.2r42
-
Locate the user account configuration file or interfaceIn the web UI, navigate to System Administration > Users or User Management. In CLI, use 'show users' or 'cat /etc/passwd' if shell access is availableAffected if The cmuser account is listed among the administrative users
-
Verify cmuser account password statusCheck whether cmuser has a password set by examining the account settings in the user management interface, or by attempting to log in with the cmuser username without providing a passwordAffected if The cmuser account exists with no password set or allows authentication with an empty password field
You are affected if your FatPipe WARP, IPVPN, or MPVPN firmware version is 5.2.0, 6.1.2, 7.1.2, 9.1.2, 10.1.2, 10.2.2 or earlier, and the cmuser account exists without a password.
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 · scopedImmediately set a strong password on or disable the cmuser account, or upgrade to FatPipe versions 10.1.2r60p91 or 10.2.2r42 or later to remediate this vulnerability.
Upgrade to FatPipe firmware version 10.1.2r60p91 or 10.2.2r42 (or later)
- Identify the FatPipe product in use (WARP, IPVPN, or MPVPN)
- Determine the current firmware version installed
- Download the fixed firmware version from FatPipe's official support portal
- Back up current configuration before upgrading
- Upgrade firmware to version 10.1.2r60p91 or 10.2.2r42 (or later)
- After upgrade, verify that the 'cmuser' account has been removed or now requires a password
- Change any default credentials on the device
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation1.0 h
- Implementation1.0 h
- Testing1.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,200.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-27856 — 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-2021-27856 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