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CVE-2016-9243

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

Published: Mar 27, 2017Updated: May 13, 2026 Sources: CVE List NVD GHSANVD-CWE-noinfo
NVD MITRE
7.5CVSSHIGH
EPSS Score
3.4%
Top 12.7%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

Description

Improper input validation in cryptography

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:NI:HA:N
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:NConfidentiality
None
I:HIntegrity
High
A:NAvailability
None
Open in CVSS calculator →

Weaknesses

NVD-CWE-noinfo

Affected Products

cryptographyPyPIOSS Libraries
cryptographycryptography.io
Library
OSS Libraries / pypi
fedorafedoraproject
On-premOS
Operating Systems / linux-distro
ubuntu linuxcanonical
On-premOS
Operating Systems / linux-distro
n/an/a
pypipackage-ecosystemOSS Libraries
cryptography.iooss-projectOSS Librariesaka cryptography
fedoraprojectoss-projectUSOperating Systemsaka fedora project
canonicalcommercialGBOperating Systemsaka canonical ltd.

Exploitability

Official Patch Available

References

https://nvd.nist.gov/vuln/detail/CVE-2016-9243
nvd.nist.gov
https://github.com/pyca/cryptography/issues/3211
github.com
https://github.com/pyca/cryptography/commit/b924696b2e8731f39696584d12cceeb3aeb2d874
github.com
and 17 more references View all →

Timeline

Published
Mar 27, 2017
Last Updated
May 13, 2026

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