CVE-2020-1918

Name: CVE-2020-1918
Creator: NVD / NIST
Published: 2021-03-10T16:15:14.377+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.5/10EPSS 1.22%

Last modified Jun 17, 2026

CVE-2020-1918 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. 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.. EPSS estimates a 1.22% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

7.5/10

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

EPSS Probability

1.22%

64.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Facebook	Hhvm	< 4.56.3
Facebook	Hhvm	>= 4.57.0, < 4.80.2
Facebook	Hhvm	>= 4.81.0, < 4.93.2
Facebook	Hhvm	4.94.0
Facebook	Hhvm	4.95.0
Facebook	Hhvm	4.96.0
Facebook	Hhvm	4.97.0
Facebook	Hhvm	4.98.0

References

https://github.com/facebook/hhvm/commit/08193b7f0cd3910256e00d599f0f3eb2519c44caPatch, Third Party Advisory
https://hhvm.com/blog/2021/02/25/security-update.htmlRelease Notes, Vendor Advisory
https://github.com/facebook/hhvm/commit/08193b7f0cd3910256e00d599f0f3eb2519c44caPatch, Third Party Advisory
https://hhvm.com/blog/2021/02/25/security-update.htmlRelease Notes, Vendor Advisory

Timeline

Published: Mar 10, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-1918?

How severe is CVE-2020-1918?

CVE-2020-1918 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 1.22% probability of exploitation in the next 30 days.

How do I fix CVE-2020-1918?

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-2020-1918?

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

Scan your code now

Source: NVD / NIST