dbcve.org
Improper Signature VerificationWeakness · CWE-347

CVE-2025-67903

MEDIUM · 5.3 CVSS v3.1 Published 2026-05-27
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
62/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click

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 · unedited
Northern.tech Mender Client 5 before 5.0.4 allows a Cryptographic signature verification bypass.

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 confidence

Northern.tech Mender Client 5 before version 5.0.4 contains a cryptographic signature verification bypass vulnerability. This flaw allows an attacker to circumvent the verification mechanism that ensures software updates are authentic and originate from trusted sources, potentially enabling the installation of malicious updates.

MitigationUpgrade Mender Client to version 5.0.4 or later to obtain the patched version with proper signature verification.

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
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify Mender Client installation and version
    Run 'mender --version' or check the package manager (dpkg -l | grep mender, rpm -qa | grep mender) to locate the Mender Client and determine its installed version number
    Affected if The installed version is found to be earlier than 5.0.4 (e.g., 5.0.3, 5.0.2, 5.0.1, 5.0.0, or any 5.x.y version below 5.0.4)
  2. Locate Mender configuration file
    Check for /etc/mender/mender.conf or the configuration file specified in the MENDER_ROOTFS_PART_DEFAULT environment variable; also look in /var/lib/mender for state files
    Affected if A valid Mender Client configuration file exists, indicating the client is actively configured on the system
  3. Verify update client is enabled
    Inspect the mender.conf file for the 'UpdateControlMap' or 'RootfsPart' configuration sections, or check if the mender-update or mender-daemon services are running via 'systemctl status mender' or 'systemctl status mender-daemon'
    Affected if The update client daemon/service is running or the update module is enabled in the configuration file
  4. Confirm signature verification is in use
    Check the mender.conf file for 'SignatureVerification' set to true, or look for 'server_certificate', 'client_protocol', or 'https_client' configuration options that indicate the client is configured to verify server authenticity
    Affected if The client is configured to fetch updates from a server and performs signature verification (this makes the bypass vulnerability relevant)
  5. Review audit logs for suspicious update activity
    Examine /var/log/mender/mender.log or journalctl -u mender for any unusual update attempts, failed signature validations, or unexpected artifact installations around the time frame of concern
    Affected if Any update logs exist showing artifact installations occurred (indicates the vulnerable feature was used)

You are affected if Mender Client 5 is installed with a version earlier than 5.0.4 and the update/signature verification feature is enabled and in use on your system.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade Mender Client to version 5.0.4 or later to obtain the patched version with proper signature verification.

Recommended fix Moderate confidence

Mender Client 5.0.4 or later

  1. Check the current Mender Client version (typically via `mender --version` or package manager)
  2. Upgrade Mender Client to version 5.0.4 or later using the appropriate package manager or installation method
  3. Verify the upgrade was successful by checking the installed version

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing4.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,340
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-67903 in production — separate from our analysis above.

No notes yet

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What this is

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.

What belongs here
  • 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