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

According to the version of the python-cryptography package installed, the EulerOS installation on the remote host is affected by the following vulnerability :

  - HKDF in cryptography before 1.5.2 returns an empty     byte-string if used with a length less than     algorithm.digest_size.(CVE-2016-9243)

Note that Tenable Network Security has extracted the preceding description block directly from the EulerOS security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

Alex Gaynor reports :

Fixed a bug where ``HKDF`` would return an empty byte-string if used with a ``length`` less than ``algorithm.digest_size``.

Markus Doring discovered that python-cryptography incorrectly handled certain HKDF lengths. This could result in python-cryptography returning an empty string instead of the expected derived key.

Note that Tenable Network Security has extracted the preceding description block directly from the Ubuntu security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

Rebase to 1.5.3 to fix CVE-2016-9243

Note that Tenable Network Security has extracted the preceding description block directly from the Fedora update system website.
Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

ID	Name	Product	Family	Severity
153317	EulerOS 2.0 SP2 : python-cryptography (EulerOS-SA-2021-2428)	Nessus	Huawei Local Security Checks	high
149123	EulerOS 2.0 SP3 : python-cryptography (EulerOS-SA-2021-1837)	Nessus	Huawei Local Security Checks	high
95515	FreeBSD : py-cryptography -- vulnerable HKDF key generation (e5dcb942-ba6f-11e6-b1cf-14dae9d210b8)	Nessus	FreeBSD Local Security Checks	high
95385	Ubuntu 16.04 LTS : python-cryptography vulnerability (USN-3138-1)	Nessus	Ubuntu Local Security Checks	high
95038	Fedora 24 : python-cryptography / python-cryptography-vectors (2016-d3a2b640ce)	Nessus	Fedora Local Security Checks	high
95017	Fedora 23 : python-cryptography / python-cryptography-vectors (2016-e77c8c1f3b)	Nessus	Fedora Local Security Checks	high
94994	Fedora 25 : python-cryptography / python-cryptography-vectors (2016-2d90e27e50)	Nessus	Fedora Local Security Checks	high

Detections

Analytics

CVE-2016-9243

high

Tenable Plugins

high

high

high

high

high

high

high