CVE-2016-9243

Publication date 9 November 2016

Last updated 25 August 2025

Ubuntu priority

Why this priority?

Cvss 3 Severity Score

Score breakdown

Description

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

Status

Show unmaintained releases

Package	Ubuntu Release	Status
python-cryptography	16.10 yakkety	Fixed 1.5-2ubuntu0.1
	16.04 LTS xenial	Fixed 1.2.3-1ubuntu0.1
	14.04 LTS trusty	Not in release
	12.04 LTS precise	Not in release

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package	Patch details
python-cryptography	Upstream: b924696

Severity score breakdown

Parameter	Value
Base score	7.5 · High
Attack vector	Network
Attack complexity	Low
Privileges required	None
User interaction	None
Scope	Unchanged
Confidentiality	None
Integrity impact	High
Availability impact	None
Vector	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

References

Related Ubuntu Security Notices (USN)

USN-3138-1
python-cryptography vulnerability
28 November 2016

Other references