Pi-hole is a DNS sinkhole that protects devices from unwanted content without installing any client-side software. From 6.4.2 until 6.5, the root-run advanced/Scripts/updatecheck.sh cron job applies truncate -s 0 and chmod 644 to /etc/pihole/versions while following symbolic links in a directory owned by the pihole user. An attacker executing as pihole can replace that path with a symlink so the scheduled root operations truncate or create an arbitrary root-owned file, or race the operations so chmod makes a sensitive target world-readable without truncating it.
This issue is fixed in version 6.5.
Attack Parameters
Attack Vector
Local
Requires local access
Attack Complexity
Low
Easy to exploit
Privileges Required
Low
Basic privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
High
Complete data leak
Integrity
High
Complete data modification
Availability
High
Complete denial of service
CVSS Vector v3.1
Weakness Type (CWE)
Vulnerable Products
pi-hole:pi-hole
References 6
https://github.com/pi-hole/pi-hole/commit/85de82dd2b63bf71ecb936177dfb82421d9d2…
security-advisories@github.com
https://github.com/pi-hole/pi-hole/commit/c1062f43b0de1876321bafac58fba86240636…
security-advisories@github.com
https://github.com/pi-hole/pi-hole/commit/e05dc3f139206fd8d0e4a052dceefb9056533…
security-advisories@github.com
https://github.com/pi-hole/pi-hole/pull/6719
security-advisories@github.com
https://github.com/pi-hole/pi-hole/releases/tag/v6.5
security-advisories@github.com
https://github.com/pi-hole/pi-hole/security/advisories/GHSA-xch2-4qxw-g5vj
security-advisories@github.com