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Vulnerability record · CVE-2016-9243 · published 27 March 2017

CVE-2016-9243: Cryptography.io cryptography vulnerability

CCryptography.Io · Cryptography

HKDF in cryptography before 1.5.2 returns an empty byte-string if used with a length less than algorithm.digest_size.

7.5 CVSS 3.1 High EPSS 3.5% · top 11.4%
7.5CVSS 3.1 base score, v2 5.0
3.5%EPSS exploitation probability, 30 days
NoNot in CISA KEV
3Affected product versions listed by NVD
18References
17 Jun 2026Last modified by NVD

Description

HKDF in cryptography before 1.5.2 returns an empty byte-string if used with a length less than algorithm.digest_size.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Affected products

3 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
http://www.openwall.com/lists/oss-security/2016/11/09/2 Mailing ListPatchVDB Entry
http://www.securityfocus.com/bid/94216 Broken LinkThird Party AdvisoryVDB Entry
http://www.ubuntu.com/usn/USN-3138-1 Third Party Advisory
https://cryptography.io/en/latest/changelog Release NotesThird Party Advisory
https://github.com/pyca/cryptography/commit/b924696b2e8731f39696584d12cceeb3aeb2d874 PatchThird Party Advisory
https://github.com/pyca/cryptography/issues/3211 Issue TrackingThird Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/5R2ZOBMPWDFFHUZ6QOZZY36 Mailing ListThird Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/U23KDR2M2N7W2ZSREG63BVW Mailing ListThird Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WQ5G7KHKZC4SI23JE7277KZ Mailing ListThird Party Advisory
http://www.openwall.com/lists/oss-security/2016/11/09/2 Mailing ListPatchVDB Entry
http://www.securityfocus.com/bid/94216 Broken LinkThird Party AdvisoryVDB Entry
http://www.ubuntu.com/usn/USN-3138-1 Third Party Advisory
https://cryptography.io/en/latest/changelog Release NotesThird Party Advisory
https://github.com/pyca/cryptography/commit/b924696b2e8731f39696584d12cceeb3aeb2d874 PatchThird Party Advisory
https://github.com/pyca/cryptography/issues/3211 Issue TrackingThird Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/5R2ZOBMPWDFFHUZ6QOZZY36 Mailing ListThird Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/U23KDR2M2N7W2ZSREG63BVW Mailing ListThird Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WQ5G7KHKZC4SI23JE7277KZ Mailing ListThird Party Advisory

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Source: NIST National Vulnerability Database (record CVE-2016-9243), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.