Headline
GHSA-9mc5-7qhg-fp3w: Below has Incorrect Permission Assignment for Critical Resource
Impact
A privilege escalation vulnerability existed in the Below service prior to v0.9.0 due to the creation of a world-writable directory at /var/log/below. This could have allowed local unprivileged users to escalate to root privileges through symlink attacks that manipulate files such as /etc/shadow.
Patches
https://github.com/facebookincubator/below/commit/10e73a21d67baa2cd613ee92ce999cda145e1a83
This is included in version 0.9.0
Workarounds
Change the permission on /var/log/below manually
References
https://www.facebook.com/security/advisories/cve-2025-27591 https://www.cve.org/CVERecord?id=CVE-2025-27591
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.