CVE-2026-44849: Portainer: Endpoint security bypass via Swarm service create/update

Synopsis

An authentication bypass vulnerability in Portainer Community Edition allows a low-privilege user to circumvent administrator-configured endpoint security restrictions by targeting the Docker Swarm service API instead of the standard container creation path. The flaw is reachable over the network and requires only a low-privilege account, with no victim interaction needed. Successful exploitation lets an attacker launch containers with privileged mode, host PID namespace, unrestricted capabilities, arbitrary bind mounts, and other dangerous configurations that administrators explicitly blocked. HarborGuard is tracking this advisory and will make a patched-image rebuild available the moment an upstream fix is published.

HarborGuard Coverage

Exploit Conditions

• Network reachabilityRequired

  The attacker must reach the Portainer service over the network; the CVSS vector specifies AV:N, meaning no local or physical access is required.

• AuthenticationRequired

  The attacker must hold a low-privilege Portainer account; admin credentials are not needed, but unauthenticated access alone is not sufficient (PR:L).

• Victim interactionNot required

  No action from another user or administrator is needed to exploit this vulnerability (UI:N).

• Attack complexityDetail

  Attack complexity is Low (AC:L), meaning the exploit is reliable and requires no special timing, race conditions, or environmental prerequisites beyond network access and a valid low-privilege account.

Blast Radius

• Attacker launches containers in privileged mode or with the host PID namespace, gaining visibility into and control over host-level processes.
• Attacker mounts arbitrary host filesystem paths into containers, reading or overwriting sensitive files including credentials, keys, and configuration data.
• Attacker loads unrestricted Linux capabilities or bypasses Seccomp and AppArmor profiles, removing kernel-level isolation from the running container.
• Because both system and subsequent scope impacts are rated High (SC:H, SI:H, SA:H), compromise can extend beyond the initial container to affect other workloads and the underlying host.