In the jose package before 0.11.0 for OCaml, library calls to validate an RSA signature only confirm that PKCS #1 decoding succeeds, and proceed to declare the signature valid without the required steps that involve the public key.
https://osv.dev/vulnerability/OSEC-2026-19
https://github.com/ulrikstrid/ocaml-jose/commit/cf17d991ec6a0d1997956b6c7799890f9c28879e