Multiple security issues have been found in the Mozilla Firefox web browser: Memory safety errors, use-after-frees and other implementation errors may lead to the execution of arbitrary code, information disclosure or privilege escalation.
For the stable distribution (jessie), these problems have been fixed in version 45.7.0esr-1~deb8u1.
For the unstable distribution (sid), these problems have been fixed in version 45.7.0esr-1 of firefox-esr and version 51.0-1 of firefox.
We recommend that you upgrade your firefox-esr 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/