Description

Gogs user can update repository content with read-only permission

Vulnerability Description

The endpoint PUT /repos/:owner/:repo/contents/* does not require write permissions and allows access with read permission only via repoAssignment().

After passing the permission check, PutContents() invokes UpdateRepoFile(), which results in:

Commit creation

Execution of git push

As a result, a token with read-only permission can be used to modify repository contents.

Attack Prerequisites

Possession of a valid access token

Read permission on the target repository (public repository or collaborator with read access)

Attack Scenario

The attacker accesses the target repository with a read-only token

The attacker sends a PUT /contents request to update an arbitrary file

The server creates a commit and performs a git push on behalf of the attacker

Potential Impact

Source code tampering

Injection of backdoors

Compromise of release artifacts and distributed packages

Mitigation

Aliases

References