What’s Vulnerable › Vulnerabilities

CVE-2020-1921

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-03-10 · updated 2026-06-17
• Weakness: CWE-121

Description

In the crypt function, we attempt to null terminate a buffer using the size of the input salt without validating that the offset is within the buffer. This issue affects HHVM versions prior to 4.56.3, all versions between 4.57.0 and 4.80.1, all versions between 4.81.0 and 4.93.1, and versions 4.94.0, 4.95.0, 4.96.0, 4.97.0, 4.98.0.

Affected products

• Facebook HHVM: before 4.56.3; from 4.57.0 before 4.80.2; from 4.81.0 before 4.93.2; 4.94.0, 4.95.0, 4.96.0, 4.97.0, 4.98.0 — fixed in 4.56.3, 4.80.2, 4.93.2

How to fix

Upgrade to a fixed version: Facebook HHVM 4.56.3, 4.80.2, 4.93.2. Check the vendor advisory for mitigations.

References

• https://github.com/facebook/hhvm/commit/08193b7f0cd3910256e00d599f0f3eb2519c44ca
• https://hhvm.com/blog/2021/02/25/security-update.html
• https://github.com/facebook/hhvm/commit/08193b7f0cd3910256e00d599f0f3eb2519c44ca
• https://hhvm.com/blog/2021/02/25/security-update.html

Get alerted when CVE-2020-1921 or the next vulnerability affects your stack