What is CVE-2016-9243?

CVE-2016-9243 is a high-severity software vulnerability with a CVSS score of 7.5. HKDF in cryptography before 1.5.2 returns an empty byte-string if used with a length less than algorithm.digest_size.

Is CVE-2016-9243 being actively exploited?

It is not currently in CISA's KEV catalog. Its EPSS exploitation probability is 3%.

What products does CVE-2016-9243 affect?

Tracked products affected include Ubuntu. Check the version you run to see whether it is affected.

How do I fix CVE-2016-9243?

Apply the vendor fix promptly. An official patch or advisory is available. Upgrade affected products to a fixed version.

← All products

CVE-2016-9243

HIGH severity · CVSS 7.5

7.5CVSS HIGH

Summary

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

Impact & exploitability

Attack vectorNetwork

Attack complexityLow

Privileges requiredNone

User interactionNone

Confidentiality impactNone

Integrity impactHigh

Availability impactNone

Exploit probability (EPSS)3%

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

Affected products we track (1)

Ubuntu

Recommendation

Apply the vendor fix promptly. Open any affected product above for its exact safe version.

Official patch: http://www.openwall.com/lists/oss-security/2016/11/09/2 ↗

Additional information

NVD record
http://www.openwall.com/lists/oss-security/2016/11/09/2Patch
https://github.com/pyca/cryptography/commit/b924696b2e8731f39696584d12cceeb3aeb2d874Patch
http://www.securityfocus.com/bid/94216Advisory
http://www.ubuntu.com/usn/USN-3138-1Advisory
https://cryptography.io/en/latest/changelogAdvisory
https://github.com/pyca/cryptography/issues/3211Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/5R2ZOBMPWDFFHUZ6QOZZY36A6H5CGJXL/Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/U23KDR2M2N7W2ZSREG63BVW7D4VC6CIZ/Advisory