Executive brief
compliance-trestle, a tool for managing compliance artifacts, contains a security flaw in how it validates web addresses. An attacker can bypass built-in protections to force the tool to connect to internal services or cloud metadata endpoints that should be restricted. This could allow an unauthorized person to steal sensitive cloud credentials or access private internal management interfaces, potentially compromising the entire cloud environment.
Technical details
The URLSecurityValidator in `trestle/core/remote/security.py` fails to properly normalize IPv4-mapped IPv6 addresses (e.g., [::ffff:169.254.169.254]), causing membership checks against IPv4-based blocklists to return False. Additionally, the validator does not include the 0.0.0.0 address in its blocked networks, which on Linux/Docker environments can route to local services. An attacker can exploit this by providing a malicious OSCAL artifact containing these bypass URLs, which are then processed by HTTPSFetcher or SFTPFetcher. This allows access to cloud metadata services (IMDS), loopback admin interfaces, and RFC 1918 private networks. The issue is fixed in version 4.1.0.
Affected products
- oscal-compass compliance-trestle <= 4.0.3
Timeline
- 2026-05-20: disclosed: Vulnerability introduced in version 4.0.3
- 2026-08-04: advisory: GitHub Advisory published
- 2026-08-12: patched: Version 4.1.0 released