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Vulnerability record · CVE-2021-24025 · published 10 March 2021

CVE-2021-24025: Facebook hhvm heap-based buffer overflow vulnerability

Facebook · Hhvm

Due to incorrect string size calculations inside the preg_quote function, a large input string passed to the function can trigger an integer overflow leading to a heap overflow. 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.

9.8 CVSS 3.1 Critical EPSS 1.7% · top 24.3% CWE-122 · Heap-based buffer overflowCWE-190 · Integer overflow
9.8CVSS 3.1 base score, v2 7.5
1.7%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
4References
17 Jun 2026Last modified by NVD

Description

Due to incorrect string size calculations inside the preg_quote function, a large input string passed to the function can trigger an integer overflow leading to a heap overflow. 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.

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

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/facebook/hhvm/commit/08193b7f0cd3910256e00d599f0f3eb2519c44ca PatchThird Party Advisory
https://hhvm.com/blog/2021/02/25/security-update.html Release NotesThird Party Advisory
https://github.com/facebook/hhvm/commit/08193b7f0cd3910256e00d599f0f3eb2519c44ca PatchThird Party Advisory
https://hhvm.com/blog/2021/02/25/security-update.html Release NotesThird Party Advisory

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Source: NIST National Vulnerability Database (record CVE-2021-24025), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.