{"id":"CVE-2016-9243","url":"https://www.cyber-defence.io/tools/cve/CVE-2016-9243","generatedAt":"2026-10-28T20:04:16.064Z","title":"HKDF in cryptography before 1.5.2 returns an empty byte-string if used with a length less than algorithm.digest_size.","description":"HKDF in cryptography before 1.5.2 returns an empty byte-string if used with a length less than algorithm.digest_size.","published":"2017-03-27T17:59:00.000Z","lastModified":"2026-06-17T00:55:43.000Z","status":"Modified","sourceIdentifier":"secalert@redhat.com","cvss":{"version":"3.1","score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N"},"cwe":[],"affected":["cryptography.io/cryptography","fedoraproject/fedora","canonical/ubuntu linux"],"epss":{"score":0.03464,"percentile":0.88991,"date":"2026-10-27","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (3.46%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[],"references":[{"url":"http://www.openwall.com/lists/oss-security/2016/11/09/2","tags":["Mailing List","Patch","VDB Entry"],"source":"secalert@redhat.com"},{"url":"http://www.securityfocus.com/bid/94216","tags":["Broken Link","Third Party Advisory","VDB Entry"],"source":"secalert@redhat.com"},{"url":"http://www.ubuntu.com/usn/USN-3138-1","tags":["Third Party Advisory"],"source":"secalert@redhat.com"},{"url":"https://cryptography.io/en/latest/changelog","tags":["Release Notes","Third Party Advisory"],"source":"secalert@redhat.com"},{"url":"https://github.com/pyca/cryptography/commit/b924696b2e8731f39696584d12cceeb3aeb2d874","tags":["Patch","Third Party Advisory"],"source":"secalert@redhat.com"},{"url":"https://github.com/pyca/cryptography/issues/3211","tags":["Issue Tracking","Third Party Advisory"],"source":"secalert@redhat.com"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/5R2ZOBMPWDFFHUZ6QOZZY36A6H5CGJXL/","tags":["Mailing List","Third Party Advisory"],"source":"secalert@redhat.com"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/U23KDR2M2N7W2ZSREG63BVW7D4VC6CIZ/","tags":["Mailing List","Third Party Advisory"],"source":"secalert@redhat.com"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WQ5G7KHKZC4SI23JE7277KZXM57GEQKT/","tags":["Mailing List","Third Party Advisory"],"source":"secalert@redhat.com"},{"url":"http://www.openwall.com/lists/oss-security/2016/11/09/2","tags":["Mailing List","Patch","VDB Entry"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"http://www.securityfocus.com/bid/94216","tags":["Broken Link","Third Party Advisory","VDB Entry"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"http://www.ubuntu.com/usn/USN-3138-1","tags":["Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://cryptography.io/en/latest/changelog","tags":["Release Notes","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://github.com/pyca/cryptography/commit/b924696b2e8731f39696584d12cceeb3aeb2d874","tags":["Patch","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://github.com/pyca/cryptography/issues/3211","tags":["Issue Tracking","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/5R2ZOBMPWDFFHUZ6QOZZY36A6H5CGJXL/","tags":["Mailing List","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/U23KDR2M2N7W2ZSREG63BVW7D4VC6CIZ/","tags":["Mailing List","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WQ5G7KHKZC4SI23JE7277KZXM57GEQKT/","tags":["Mailing List","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2016-9243","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}