dbcve.org
Versa Operating SystemOperating system · Versa Networks

CVE-2018-16495

HIGH · 8.8 CVSS v3.1 Published 2021-05-26
Fix available
A fix is available. Upgrade to 16.1r2s11 / 20.2.2 or later.
See remediation →
94/100
Remediation priority · Urgent
Remotely reachable 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
In VOS user session identifier (authentication token) is issued to the browser prior to authentication but is not changed after the user successfully logs into the application. Failing to issue a new session ID following a successful login introduces the possibility for an attacker to set up a trap session on the device the victim is likely to login with.

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 confidence

VOS suffers from a session fixation vulnerability where a session identifier is issued to the browser prior to user authentication, but the application fails to regenerate a new session ID after successful login. This allows an attacker who has obtained the pre-authentication session ID to maintain access to the session after the user logs in, effectively hijacking the authenticated session.

MitigationImplement session ID regeneration immediately after successful authentication by issuing a new session identifier and invalidating the pre-authentication session, ensuring the old session ID cannot be used post-login.

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
Versa Operating SystemOperating system
Affected:< 16.1r2s11>= 20.2.0, < 20.2.2>= 21.1.0, < 21.1.1

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

CVSS:3.1/AV:N/AC:L/PR:L/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 checks

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

  1. Check VOS version
    Access the Versa CLI and run 'show system version' or 'show version' to obtain the installed VOS version number
    Affected if The installed version is < 16.1r2s11, OR >= 20.2.0 and < 20.2.2, OR >= 21.1.0 and < 21.1.1
  2. Verify web portal is enabled
    Run 'show web-manager status' or check the web UI service configuration in the CLI to confirm the Versa web portal interface is enabled
    Affected if The web portal is enabled and the version is in the affected ranges listed above
  3. Check session management configuration
    In the CLI, run 'show web-manager session' or examine the session timeout and session ID settings under the web-manager configuration context
    Affected if Session regeneration after authentication is not explicitly configured or the default behavior is in use with an affected version
  4. Identify exposed login interface
    Confirm that the Versa web login page is accessible externally or internally by accessing the device IP or hostname via HTTPS on ports 443 or 8443
    Affected if The login page is accessible and the VOS version is in the affected ranges

You are affected if the installed VOS version falls within any of the affected ranges AND the web portal interface is enabled, as the session fixation flaw requires the pre-authentication session to be usable.

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
Upgrade available Upgrade to 16.1r2s11 / 20.2.2 / 21.1.1 or later
Fixed in 16.1r2s1120.2.221.1.1
Interim mitigation

Implement session ID regeneration immediately after successful authentication by issuing a new session identifier and invalidating the pre-authentication session, ensuring the old session ID cannot be used post-login.

Recommended fix High confidence

16.1r2s11 (for 16.1.x branch), 20.2.2 (for 20.2.x branch), or 21.1.1 (for 21.1.x branch)

  1. 1. Identify the currently installed Versa Operating System version using 'show version' command
  2. 2. Determine which upgrade path applies based on your current version branch
  3. 3. If running < 16.1r2s11, upgrade to 16.1r2s11 or later in the 16.1.x train
  4. 4. If running >= 20.2.0 and < 20.2.2, upgrade to 20.2.2 or later in the 20.2.x train
  5. 5. If running >= 21.1.0 and < 21.1.1, upgrade to 21.1.1 or later in the 21.1.x train
  6. 6. Download the appropriate software image from Versa Networks support portal
  7. 7. Follow standard Versa OS upgrade procedures including backup of configuration
  8. 8. After upgrade, verify the new version is running with 'show version'
Caveat Review Versa Networks release notes for your version branch for any configuration or feature changes that may require adjustment

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

Fix this in Versa Operating System Scoped from the published advisory
  • Consultation4.0 h
  • Implementation16.0 h
  • Testing8.0 h
  • Review / QA4.0 h
32.0 hours of engineering $5,600
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $8,960.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2018-16495 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

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-2018-16495 in production — separate from our analysis above.

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.

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