CVE-2026-91778
Received Received - Intake

Arbitrary Script Execution in Octopus Server via Permission Bypass

Publication date: 2026-09-15

Last updated on: 2026-09-15

Assigner: Octopus Deploy

Description
In affected versions of Octopus Server, users with certain scoped permission sets could execute arbitrary scripts on a worker (including the Octopus Server built-in worker). Incorrect permission validation during script execution would allow the script to execute without the user possessing the required authorisation.

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Meta Information

Published
2026-09-15
Last Modified
2026-09-15
Generated
2026-09-15
AI Q&A
2026-09-15
EPSS Evaluated
N/A
NVD
CVE-2026-91778
EUVD
EUVD-2026-78314

Affected Vendors & Products

Showing 4 associated CPEs
Vendor Product Version / Range
octopus octopus_server From 2019.x (inc) to 2026.1.11725 (exc)
octopus octopus_server 2026.1.11725
octopus octopus_server 2026.2.13344
octopus octopus_server 2026.3.15816

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-863 The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.

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Executive Summary

This vulnerability in Octopus Server allows users with certain scoped permissions to execute arbitrary scripts on a worker, including the built-in Octopus Server worker, without proper authorization. It occurs due to incorrect permission validation during script execution.

Detection Guidance

To detect this vulnerability, check the version of your Octopus Server. If it is between 2019.x and 2026.3.x and not one of the patched versions (2026.1.11725, 2026.2.13344, 2026.3.15816), it is likely vulnerable. Review user permissions for script execution capabilities.

Impact Analysis

An attacker with scoped permissions could run malicious scripts on a worker, potentially leading to unauthorized access, data breaches, or system compromise. This includes the Octopus Server built-in worker, increasing the risk of server-level attacks.

Compliance Impact

This vulnerability could lead to unauthorized data access or exfiltration, violating GDPR's data protection requirements or HIPAA's safeguards for protected health information. Non-compliance may result in legal penalties or reputational damage.

Mitigation Strategies

Immediately upgrade to a patched version of Octopus Server: 2026.1.11725, 2026.2.13344, or 2026.3.15816. Octopus Cloud users are already protected. If upgrading is not possible, restrict user permissions to prevent unauthorized script execution.

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