The CreateSubAgent RPC in github.com/coder/coder/v2 did not enforce the template's MaxPortSharingLevel when registering sub-agent apps, allowing a workspace owner with an agent token to register a sub-agent app with a sharing level exceeding the administrator-configured maximum. This flaw permits setting the sharing level to PUBLIC even if the template restricts it to owner-only, exposing the app to unauthenticated users via wildcard app hostnames. Exploitation requires authenticated access as a workspace owner with an agent token and affects deployments using Enterprise port-sharing policies with wildcard app hostnames. The issue is tracked as CVE-2026-55432 and CWE-862 (Missing Authorization). The vendor released official patches in versions 2.34.2, 2.33.8, 2.32.7, and 2.29.17, which clamp the sub-agent app sharing level to the template's MaxPortSharingLevel. A workaround is to disable wildcard app hostnames (CODER_WILDCARD_ACCESS_URL).

An authenticated workspace owner with an agent token can bypass the configured maximum port-sharing level by registering a sub-agent app with a higher sharing level than allowed by the template. This can expose the app to unauthenticated users via wildcard app domains, potentially leaking information or access beyond intended limits. The impact is limited to environments using Enterprise port-sharing policies with wildcard app hostnames and requires authenticated access with sufficient privileges. There is no indication of denial of service or integrity impact.

Apply the official patches available in versions 2.34.2, 2.33.8, 2.32.7, or 2.29.17 to ensure the sub-agent app sharing level is properly clamped to the template's MaxPortSharingLevel. If immediate patching is not possible, disable wildcard app hostnames (CODER_WILDCARD_ACCESS_URL) to block subdomain-based app routing and prevent exposure via wildcard domains.