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Octopus ServerApplication · Octopus

CVE-2026-4881

MEDIUM · 6.5 CVSS v3.1 Published 2026-06-04
Fix available
A fix is available. Upgrade to 2025.4.10545 / 2026.1.11313 or later.
See remediation →
71/100
Remediation priority · Elevated
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 affected versions of Octopus Server, permissions were not checked correctly resulting in any authenticated user being able to make server level changes using a certain API endpoint despite receiving an error.

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

In Octopus Server, an authorization bypass exists where any authenticated user can perform server-level changes through a specific API endpoint despite receiving an error, due to improper permission validation that occurs after the action is executed.

MitigationApply the vendor patch for Octopus Server that implements proper permission checking before allowing server-level API operations.

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
Octopus ServerApplication
Affected:>= 2023.1.4189, < 2025.4.10545>= 2026.1.675, < 2026.1.11313

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
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/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. Confirm Octopus Server is installed
    Identify whether Octopus Server is running in the environment by checking for the Octopus Server process, service, or web application accessible on the default Octopus port (usually 80/443 or configured port).
    Affected if Octopus Server is found running in the environment
  2. Determine installed Octopus Server version
    Retrieve the version number of the Octopus Server installation. This is typically available through the Octopus web interface (System -> About), the Octopus Manager application, or by querying the server's API/health endpoint.
    Affected if Version cannot be determined or is not clearly displayed
  3. Compare version against affected ranges
    Check if the installed version falls within either of these ranges: >= 2023.1.4189 AND < 2025.4.10545, OR >= 2026.1.675 AND < 2026.1.11313.
    Affected if Installed version matches one of the affected version ranges (vulnerable to privilege escalation)
  4. Verify API access is enabled
    Confirm that the Octopus Server API endpoint that handles server-level administrative actions is accessible. This can be verified by checking if the web interface or API is reachable and authentication is enabled.
    Affected if API access is enabled and the server is running a vulnerable version

A user is affected if they are running a vulnerable Octopus Server version (within the specified ranges) with API access enabled, allowing any authenticated user to potentially escalate privileges to server-level administrative actions.

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 2025.4.10545 / 2026.1.11313 or later
Fixed in 2025.4.105452026.1.11313
Interim mitigation

Apply the vendor patch for Octopus Server that implements proper permission checking before allowing server-level API operations.

Recommended fix High confidence

2025.4.10545 or later (for 2023.1.x line); 2026.1.11313 or later (for 2026.1.x line)

  1. 1. Back up your Octopus Server database and configuration files before upgrading.
  2. 2. Download the latest Octopus Server installer from the official Octopus Deploy downloads page.
  3. 3. Stop the Octopus Server service.
  4. 4. Run the installer and follow the upgrade prompts, or use your preferred deployment method.
  5. 5. Start the Octopus Server service after upgrade completes.
  6. 6. Verify that the server is functioning correctly and test the affected API endpoint to confirm the authorization check is now enforced.
Caveat Review Octopus Server release notes for breaking changes between your current version and the target version

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

Fix this in Octopus Server Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing8.0 h
  • Review / QA4.0 h
24.0 hours of engineering $4,160
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $6,656.

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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-2026-4881 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