SPIP 3.1.x suffer from a Reflected Cross Site Scripting Vulnerability in /ecrire/exec/info_plugin.php involving the $plugin parameter, as demonstrated by a /ecrire/?exec=info_plugin URL.
Exploitability
AV:NAC:LPR:NUI:RScope
S:CImpact
C:LI:LA:N6.1/CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N