CVE-2016-9243
published 2017-03-27CVE-2016-9243: HKDF in cryptography before 1.5.2 returns an empty byte-string if used with a length less than algorithm.digest_size.
PriorityP336high7.5CVSS 3.1
AVNACLPRNUINSUCNIHAN
EPSS
3.40%
87.5th percentile
HKDF in cryptography before 1.5.2 returns an empty byte-string if used with a length less than algorithm.digest_size.
Affected
8 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| canonical | ubuntu_linux | — | — |
| canonical | ubuntu_linux | — | — |
| cryptography.io | cryptography | <= 1.5.2 | — |
| cryptography.io | cryptography | >= 0 < 1.5.3 | 1.5.3 |
| debian | python-cryptography | < python-cryptography 1.5.3-1 (bookworm) | python-cryptography 1.5.3-1 (bookworm) |
| fedoraproject | fedora | — | — |
| fedoraproject | fedora | — | — |
| fedoraproject | fedora | — | — |
CVSS provenance
nvdv3.17.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
nvdv2.05.0MEDIUMAV:N/AC:L/Au:N/C:N/I:P/A:N
osv7.5HIGH
vendor_debian7.5HIGH
vendor_redhat7.5HIGH
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Ubuntu
python-cryptography vulnerability
vendor_ubuntu·2016-11-28
CVE-2016-9243 python-cryptography vulnerability
Title: python-cryptography vulnerability
Summary: python-cryptography could generate incorrect keys.
Markus Döring 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.
Instructions: In general, a standard system update will make all the necessary changes.
Red Hat
python-cryptography: HKDF might return an empty byte-string
vendor_redhat·2016-11-05·CVSS 7.5
CVE-2016-9243 [HIGH] CWE-327 python-cryptography: HKDF might return an empty byte-string
python-cryptography: HKDF might return an empty byte-string
HKDF in cryptography before 1.5.2 returns an empty byte-string if used with a length less than algorithm.digest_size.
Package: python-cryptography (Red Hat Enterprise Linux 7) - Not affected
Package: python-cryptography (Red Hat Enterprise Linux OpenStack Platform 7 (Kilo)) - Will not fix
Package: python-cryptography (Red Hat OpenStack Platform 10 (Newton)) - Will not fix
Package: python-cryptography (Red Hat OpenStack Platform 8 (Liberty)) - Will not fix
Package: python-cryptography (Red Hat OpenStack Platform 9 (Mitaka)) - Will not fix
Debian
CVE-2016-9243: python-cryptography - HKDF in cryptography before 1.5.2 returns an empty byte-string if used with a le...
vendor_debian·2016·CVSS 7.5
CVE-2016-9243 [HIGH] CVE-2016-9243: python-cryptography - HKDF in cryptography before 1.5.2 returns an empty byte-string if used with a le...
HKDF in cryptography before 1.5.2 returns an empty byte-string if used with a length less than algorithm.digest_size.
Scope: local
bookworm: resolved (fixed in 1.5.3-1)
bullseye: resolved (fixed in 1.5.3-1)
forky: resolved (fixed in 1.5.3-1)
sid: resolved (fixed in 1.5.3-1)
trixie: resolved (fixed in 1.5.3-1)
OSV
Improper input validation in cryptography
osv·2022-05-17
CVE-2016-9243 [HIGH] Improper input validation in cryptography
Improper input validation in cryptography
HKDF in cryptography before 1.5.3 returns an empty byte-string if used with a length less than algorithm.digest_size.
GHSA
Improper input validation in cryptography
ghsa·2022-05-17
CVE-2016-9243 [HIGH] CWE-20 Improper input validation in cryptography
Improper input validation in cryptography
HKDF in cryptography before 1.5.3 returns an empty byte-string if used with a length less than algorithm.digest_size.
OSV
CVE-2016-9243: HKDF in cryptography before 1
osv·2017-03-27·CVSS 7.5
CVE-2016-9243 [HIGH] CVE-2016-9243: HKDF in cryptography before 1
HKDF in cryptography before 1.5.2 returns an empty byte-string if used with a length less than algorithm.digest_size.
No detection rules found.
No public exploits indexed.
arXiv
SAGA: Detecting Security Vulnerabilities Using Static Aspect Analysis
arxiv_fulltext·2026-01-21
SAGA: Detecting Security Vulnerabilities Using Static Aspect Analysis
[SAGA: Detecting Security Vulnerabilities Using Static Aspect Analysis]SAGA: Detecting Security Vulnerabilities Using Static Aspect Analysis
Yoann Marquer
[email protected]
0000-0002-4607-967X
Domenico Bianculli
[email protected]
0000-0002-4854-685X
Interdisciplinary Centre for Security, Reliability, and Trust (SnT), University of Luxembourg
Luxembourg
Lionel C. Briand
[email protected]
0000-0002-1393-1010
School of Electrical and Computer Engineering, University of Ottawa
Canada
Lero SFI Centre for Software Research, University of Limerick
Ireland
## Abstract
Python is one of the most popular programming languages; as such, projects written in Python involve an increasing number of diverse security vulnerabilities.
However, existing state-of-the-art analysis tools for
Bugzilla
CVE-2016-9243 python-cryptography: HKDF might return an empty byte-string
bugzilla·2016-11-09·CVSS 7.5
CVE-2016-9243 [HIGH] CVE-2016-9243 python-cryptography: HKDF might return an empty byte-string
CVE-2016-9243 python-cryptography: HKDF might return an empty byte-string
Cryptography 1.5.3 release fixed one security issue.
HKDF would return an empty byte-string if used with a length less than algorithm.digest_size.
References:
https://cryptography.io/en/latest/changelog/#id1
Upstream bug:
https://github.com/pyca/cryptography/issues/3211
Upstream patch:
https://github.com/pyca/cryptography/commit/b924696b2e8731f39696584d12cceeb3aeb2d874
Discussion:
Created python-cryptography tracking bugs for this issue:
Affects: fedora-all [bug 1393432]
---
Data returned by the HKDF() are deemed to be cryptographically strong keys, which can be used by other cryptrographical primitives like ciphers to encrypt secret data. When HKDF() returns empty strings, then depending on the primitiv
Bugzilla
CVE-2016-9243 python-cryptography: HKDF might return an empty byte-string [fedora-all]
bugzilla·2016-11-09·CVSS 7.5
CVE-2016-9243 [HIGH] CVE-2016-9243 python-cryptography: HKDF might return an empty byte-string [fedora-all]
CVE-2016-9243 python-cryptography: HKDF might return an empty byte-string [fedora-all]
This is an automatically created tracking bug! It was created to ensure
that one or more security vulnerabilities are fixed in affected versions
of Fedora.
For comments that are specific to the vulnerability please use bugs filed
against the "Security Response" product referenced in the "Blocks" field.
For more information see:
http://fedoraproject.org/wiki/Security/TrackingBugs
When submitting as an update, use the fedpkg template provided in the next
comment(s). This will include the bug IDs of this tracking bug as well as
the relevant top-level CVE bugs.
Please also mention the CVE IDs being fixed in the RPM changelog and the
fedpkg commit message.
NOTE: this issue affects multiple supported ver
http://www.openwall.com/lists/oss-security/2016/11/09/2http://www.securityfocus.com/bid/94216http://www.ubuntu.com/usn/USN-3138-1https://cryptography.io/en/latest/changeloghttps://github.com/pyca/cryptography/commit/b924696b2e8731f39696584d12cceeb3aeb2d874https://github.com/pyca/cryptography/issues/3211https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/5R2ZOBMPWDFFHUZ6QOZZY36A6H5CGJXL/https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/U23KDR2M2N7W2ZSREG63BVW7D4VC6CIZ/https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WQ5G7KHKZC4SI23JE7277KZXM57GEQKT/http://www.openwall.com/lists/oss-security/2016/11/09/2http://www.securityfocus.com/bid/94216http://www.ubuntu.com/usn/USN-3138-1https://cryptography.io/en/latest/changeloghttps://github.com/pyca/cryptography/commit/b924696b2e8731f39696584d12cceeb3aeb2d874https://github.com/pyca/cryptography/issues/3211https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/5R2ZOBMPWDFFHUZ6QOZZY36A6H5CGJXL/https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/U23KDR2M2N7W2ZSREG63BVW7D4VC6CIZ/https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WQ5G7KHKZC4SI23JE7277KZXM57GEQKT/
2017-03-27
Published