CVE-2021-24025

9.8 criticalEPSS 1.7%

Critical (9.8) in facebook hhvm. EPSS 1.7% chance of exploitation in the next 30 days.

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.

Severity

CVSS 3.1

9.8 critical

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

EPSS: 1.7% chance of exploitation in the next 30 days; higher than 76% of CVEs (scores of 2026-10-31)
CWEs: CWE-190, CWE-122
Published: 2021-03-10
Modified: 2026-06-17
Record from: the NVD, synced 2026-10-19

Affected

facebook:hhvm

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

Check your stack JSON