Jansson, possibly 2.4 and earlier, does not restrict the ability to trigger hash collisions predictably, which allows context-dependent attackers to cause a denial of service (CPU consumption) via a crafted JSON document.
{ "urgency": "not yet assigned" }
"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2013-6401.json"