Security Advisory 2026-16
| Summary | Invitation codes written to audit event log |
| Advisory Number | 2026-16 |
| Discovery Date | 28 AUG 2026 |
| Patch Release Date | 18 SEP 2026 |
| Advisory Release Date | 27 OCT 2026 |
| Product | Octopus Server |
| Operating System | Linux and Microsoft Windows |
| Severity | High |
| CVE ID | CVE-2026-117341 |
Customers who have downloaded and installed any of the Octopus Server versions listed below ("Details") are affected.
Please upgrade your Octopus Server immediately to fix this vulnerability.
Customers who have upgraded Octopus Server to version 2026.3.15829 or higher are not affected.
Severity
Octopus Deploy has given this vulnerability a High rating. This rating was given according to the Octopus Deploy severity levels, which ranks vulnerabilities as critical, high, medium, or low severity.
This is our assessment and you should evaluate its applicability to your own environment.
Details
In affected versions of Octopus Server, creating a user invitation writes the invitation code to the audit event log. When the invitation is linked to a space, a user in that space with appropriate permissions could read the code from the audit event. Successfully exploiting this by redeeming the unclaimed invitation could allow the user to escalate privileges however this is dependant on the permissions assigned for the invited user.
The versions of Octopus Server affected by this vulnerability are:
- All 2019.x, 2020.x, 2021.x, 2022.x, 2023.x 2024.x and 2025.x versions
- All 2026.x versions before 2026.2.13438
- All 2026.3 versions before 2026.3.15829
Octopus Cloud customers do not need to take any further action as all instances have been updated to the patched version.
Fix
To address this vulnerability, we have released Octopus Server version:
- 2026.2.13438
- 2026.3.15829
The latest versions of Octopus Deploy products can be downloaded from https://octopus.com/downloads and previous versions can be downloaded from https://octopus.com/downloads/previous
What You Need to Do
Octopus Deploy recommends that you upgrade to the latest version (2026.3.15973). You can download the latest version of Octopus Server from https://octopus.com/downloads
If you can't upgrade to the latest version (2026.3.15973):
| If you have feature version... | ...then upgrade to this version |
|---|---|
| 2019.x, 2020.x 2021.x 2022.x 2023.x 2024.x, 2025.x | 2026.2.13434 or greater |
| 2026.1.x | 2026.2.13434 or greater |
| 2026.2.x | 2026.2.13434 or greater |
| 2026.3.x | 2026.3.15829 or greater |
Mitigation
There is no known mitigation for CVE-2026-117341, it is important to upgrade to a fixed version as soon as possible.
Support
If you have any questions or concerns regarding this advisory, please contact our support team https://octopus.com/support.
Exploitation and Public Announcements
The Octopus Deploy security team is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory.
Source
This vulnerability was found during internal testing by Nathan Willoughby at Octopus Deploy