Fariskhi Vidyan and Thomas Jarosch discovered several vulnerabilities in php-horde-image, the image processing library for the Horde groupware suite. They would allow an attacker to cause a denial-of-service or execute arbitrary code.
For the stable distribution (stretch), these problems have been fixed in version 2.3.6-1+deb9u1.
We recommend that you upgrade your php-horde-image packages.
Further information about Debian Security Advisories, how to apply these updates to your system and frequently asked questions can be found at: https://www.debian.org/security/