What’s Vulnerable › Vulnerabilities

CVE-2020-1918

• 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-127

Description

In-memory file operations (ie: using fopen on a data URI) did not properly restrict negative seeking, allowing for the reading of memory prior to the in-memory 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

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