The ressol function in Botan before 1.10.11 and 1.11.x before 1.11.27 allows remote attackers to cause a denial of service (infinite loop) via unspecified input to the OS2ECP function, related to a composite modulus.
https://security.gentoo.org/glsa/201612-38
http://www.debian.org/security/2016/dsa-3565
http://marc.info/?l=botan-devel&m=145449001708138&w=2