CVE-2026-4881

In affected versions of Octopus Server, a user with permission to upload a malicious nuget package can deploy a script step so the script executes outside of the parent directory.

In affected versions of Octopus Server, a user holding the System Manager role could escalate their privileges to full system Administrator.

In Octopus Server, creating a user invitation writes the invitation code to the audit event log. A user in the linked space with appropriate permissions could read the code and redeem the unclaimed invitation to escalate privileges, depending on the permissions assigned to the invited user.

In affected versions of Octopus Server, OIDC token issuer validation was performed inconsistently. This could result in a token issued from a suitably configured non-legitimate issuer being accepted as a token belonging to a service account from a legitimate trusted issuer. Exploitation requires a service account with at least one OIDC identity configured, and the attacker would also need to know or guess some details of that identity.

In affected versions of Octopus Server, users with certain scoped permission sets could execute arbitrary scripts in an environment without possessing the required authorization.

In affected versions of Octopus Server with the LDAP authentication provider enabled, any authenticated user could call the LDAP user search and LDAP group search.

Octopus Server incorrectly evaluates multiple scoped permission assignments, allowing a highly privileged user to obtain deployment permissions beyond those actually granted. This affects versions with the flawed permission evaluation logic.

In affected versions of Octopus Server, an authenticated user with permission to modify roles could bypass the protections preventing access abuse resulting in privilege escalation. It was possible for the built-in role to be weakened and the attacker's account added to a privileged team. This was achievable due to improper validation of unsafe equivalence in inputs.

In affected versions of Octopus Server, an authenticated user with permissions to edit an Environment or Project can set specifically crafted JSON content. Insecure deserialization of this content allows arbitrary code execution in the Octopus Server process.

In affected versions of Octopus Server, a user with permission to modify non built-in external feeds could exploit a path traversal flaw to overwrite arbitrary files on the server, potentially leading to remote code execution in some configurations.