Gogs is an open source self-hosted Git service. Prior to 0.14.3, organization names containing path traversal sequences (../) are accepted by Gogs, and repositories under them are written to paths following these path traversals. This allows storing/retrieving data for repositories at arbitrary locations on the filesystem. By creating nested structure of Git repositories, one can overwrite the other's hooks configuration to result in Remote Code Execution (RCE). This vulnerability is fixed in 0.14.3.

Affected: Go: gogs.io/gogs

### Summary

Organization names containing path traversal sequences (`../`) are accepted by Gogs, and repositories under them are written to paths following these path traversals. This allows storing/retrieving data for repositories at arbitrary locations on the filesystem. By creating nested structure of Git repositories, one can overwrite the other's `hooks` configuration to result in Remote Code Execution (RCE).

### Details

During organization creation, `internal/database/org.go` calls `os.MkdirAll(repox.UserPath(org.Name))` without sanitizing `org.Name`.

https://github.com/gogs/gogs/blob/d7571322a04a29476d4241406ed50bf7eef0a5b7/internal/database/org.go#L165

Repository creation uses this name to decide where to write the Git bare repository's (`org/name.git`). By setting the org name to `../../../../tmp/test`, and creating a repository under that organization, it gets written under `/tmp/test` on the server.

https://github.com/gogs/gogs/blob/d7571322a04a29476d4241406ed50bf7eef0a5b7/internal/repox/repox.go#L57-L58

An attacker can abuse this in a clever way by writing to the `/data/gogs/data/tmp/local-r/1` directory, being a local worktree of the git repositories inside of Gogs. These directories are editable by Git. By creating a repository nested inside of there, files like `config` and `hooks/update` are now referenced through the path traversal, and are editable by Git. This allows the attacker to edit the `hooks/update` script with malicious Bash commands and th…

Ein Angreifer kann mehrere Schwachstellen in Gogs ausnutzen, um erweiterte Berechtigungen zu erlangen, beliebigen Code auszuführen – sogar mit erweiterten Berechtigungen, was zur vollständigen Kontrolle über das System führen kann –, Sicherheitsmaßnahmen zu umgehen, Daten zu manipulieren, Cross-Site-Scripting-Angriffe durchzuführen, Benutzer auf bösartige Websites umzuleiten oder einen Denial-of-Service-Zustand zu verursachen.