The porte_plume plugin used by SPIP before 4.30-alpha2, 4.2.13, and 4.1.16 is vulnerable to an arbitrary code execution vulnerability. A remote and unauthenticated attacker can execute arbitrary PHP as the SPIP user by sending a crafted HTTP request.
https://vulncheck.com/advisories/spip-porte-plume
https://thinkloveshare.com/hacking/spip_preauth_rce_2024_part_1_the_feather/