An issue was discovered in Mbed TLS before 2.25.0 (and before 2.16.9 LTS and before 2.7.18 LTS). The calculations performed by mbedtls_mpi_exp_mod are not limited; thus, supplying overly large parameters could lead to denial of service when generating Diffie-Hellman key pairs.
https://lists.debian.org/debian-lts-announce/2022/12/msg00036.html
https://lists.debian.org/debian-lts-announce/2021/11/msg00021.html
https://github.com/ARMmbed/mbedtls/releases/tag/v2.7.18
https://github.com/ARMmbed/mbedtls/releases/tag/v2.25.0
https://github.com/ARMmbed/mbedtls/releases/tag/v2.16.9
https://cert-portal.siemens.com/productcert/pdf/ssa-756638.pdf