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.
https://hackerone.com/reports/407552
Source: Mitre, NVD
Published: 2018-11-23
Updated: 2026-06-17
Base Score: 6.5
Vector: CVSS2#AV:N/AC:L/Au:S/C:P/I:P/A:P
Severity: Medium
Base Score: 7.2
Vector: CVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
Severity: High
EPSS: 0.0231