ThinLinc 4.15.1 through 4.20.1 security release

[CendioOssman]

Details are now available on how to detect if this vulnerability has been exploited:

Ruling out that the 2026-04-08 security issue was exploited

This post provides guidance for verifying that the vulnerability discovered on 2026-04-08 has not been exploited on a ThinLinc cluster. See this announcement for more information and instructions for updating your ThinLinc installation: Note that we have not seen any indication that this vulnerability has been used by malicious actors in the wild. Directly ruling out exploitation If there have been no logins through Web Access, exploitation can be directly ruled out. This needs to be verifie…