tugtainer: Improper Access Control
CVE-2026-55181 is a critical-severity improper access control vulnerability in tugtainer from Quenary, with a CVSS 3.1 base score of 9.4 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected tugtainer versions: < 1.30.3. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.6% chance of exploitation within 30 days, which is low compared with other CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Check which version of tugtainer you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on github.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- LowPerformance or availability is reduced.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L. Scored by CNA (github.com).
Official description
Tugtainer is a self-hosted app for automating updates of Docker containers. Prior to version 1.30.3, Tugtainer's OIDC authentication can still be initiated even when OIDC_ENABLED=false. The /auth/oidc/enabled endpoint correctly reports that OIDC is disabled. However, a direct request to /auth/oidc/login still starts the OIDC login flow, returns HTTP 302, sets an oidc_state cookie, and redirects the user to the configured OIDC authorization endpoint. This bypasses the intended OIDC disable switch. This issue has been patched in version 1.30.3.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Access Control
The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor.
How developers prevent this class of flaw
- Very carefully manage the setting, management, and handling of privileges. Explicitly manage trust zones in the software.
- Compartmentalize the system to have safe areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area. Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: poc, automatable: yes, technical impact: total).
References
Patches and release notes
Other vulnerabilities in tugtainer
- 8.1 High severity
- 9.1 Critical severity
- 9.8 Critical severity
- 9.9 Critical severity
- 9.1 Critical severity
- 9.8 Critical severity
Recent Improper Access Control vulnerabilities
- 7.2 High severity
- 8.6 High severity
- 7.1 High severity
- 8.8 High severity
- 9.6 Critical severity
- 9.3 Critical severity
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