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Remote code execution in Nextcloud Flow via vulnerable Windmill version

High
nickvergessen published GHSA-g7vj-98x3-qvjf Mar 6, 2026

Package

Flow (Nextcloud)

Affected versions

>= 1.0.0, >= 1.1.0, >= 1.2.0

Patched versions

1.3.0

Description

Impact

An unauthentified attacker, can find the SUPERADMIN_SECRET and use it to login as a super admin. This could allow the attacker to compromise the server within the Flow container and

  • read arbitrary files,
  • leak the windmill_users_config.json file containing admin tokens in plaintext,
  • and use the leaked tokens to achieve remote code execution as root within the container.

Recommendation

To prevent attackers from exploiting the reported issue, we strongly recommend that the Nextcloud Flow app is upgraded as soon as possible to the 1.3.0 release, which was released 13. January 2026.
Until the upgrade, the Flow external app should be disabled and the container turned off.

Workarounds

The only workaround is to disable the Flow app and make sure the container is turned off and does not restart

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Adjacent
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVE ID

CVE-2026-29059

Weaknesses

No CWEs