CVE-2016-20013

Name: CVE-2016-20013
Creator: NVD / NIST
Published: 2022-02-19T05:15:09.413+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.5/10EPSS 2.20%

Last modified Jun 17, 2026

CVE-2016-20013 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. sha256crypt and sha512crypt through 0.6 allow attackers to cause a denial of service (CPU consumption) because the algorithm's runtime is proportional to the square of the length of the password.. EPSS estimates a 2.20% chance of exploitation in the next 30 days.

Description

sha256crypt and sha512crypt through 0.6 allow attackers to cause a denial of service (CPU consumption) because the algorithm's runtime is proportional to the square of the length of the password.

Metrics

CVSS 3.1

7.5/10

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

EPSS Probability

2.20%

80.2th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-770

Affected Software

Vendor	Product	Versions
Sha256crypt Project	Sha256crypt	<= 0.6
Sha512crypt Project	Sha512crypt	<= 0.6

References

https://akkadia.org/drepper/SHA-crypt.txtExploit, Third Party Advisory
https://pthree.org/2018/05/23/do-not-use-sha256crypt-sha512crypt-theyre-dangerous/Exploit, Third Party Advisory
https://twitter.com/solardiz/status/795601240151457793Third Party Advisory
https://akkadia.org/drepper/SHA-crypt.txtExploit, Third Party Advisory
https://pthree.org/2018/05/23/do-not-use-sha256crypt-sha512crypt-theyre-dangerous/Exploit, Third Party Advisory
https://twitter.com/solardiz/status/795601240151457793Third Party Advisory

Timeline

Published: Feb 19, 2022
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2016-20013?

sha256crypt and sha512crypt through 0.6 allow attackers to cause a denial of service (CPU consumption) because the algorithm's runtime is proportional to the square of the length of the password.

How severe is CVE-2016-20013?

CVE-2016-20013 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 2.20% probability of exploitation in the next 30 days.

How do I fix CVE-2016-20013?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2016-20013?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST