What’s Vulnerable › Vulnerabilities

CVE-2016-20013

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 2.2% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2022-02-19 · updated 2026-06-17
• Weakness: CWE-770

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.

Affected products

• Sha256Crypt Project Sha256Crypt: through 0.6
• Sha512Crypt Project Sha512Crypt: through 0.6

References

• https://akkadia.org/drepper/SHA-crypt.txt
• https://pthree.org/2018/05/23/do-not-use-sha256crypt-sha512crypt-theyre-dangerous/
• https://twitter.com/solardiz/status/795601240151457793
• https://akkadia.org/drepper/SHA-crypt.txt
• https://pthree.org/2018/05/23/do-not-use-sha256crypt-sha512crypt-theyre-dangerous/
• https://twitter.com/solardiz/status/795601240151457793

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