Vanilla before 2.5.5 and 2.6.x before 2.6.2 allows Remote Code Execution because authenticated administrators have a reachable call to unserialize in the Gdn_Format class.
Severity
CVSS 3.0
7.2 high
CVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
EPSS
2.0% chance of exploitation in the next 30 days; higher than 80% of CVEs (scores of 2026-10-31)