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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (2.17%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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.
- CVSS 3.1
- 7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 2.17% probability · 82th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-770
- Affected
- sha256crypt project/sha256crypt · sha512crypt project/sha512crypt
- Source
- cve@mitre.org
EPSS 2.2% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
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
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.