CVE-2021-24036

Name: CVE-2021-24036
Creator: NVD / NIST
Published: 2021-07-23T01:15:07.073+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 3.28%

Last modified Jun 17, 2026

CVE-2021-24036 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. Passing an attacker controlled size when creating an IOBuf could cause integer overflow, leading to an out of bounds write on the heap with the possibility of remote code execution. This issue affects versions of folly prior to v2021.07.22.00. EPSS estimates a 3.28% chance of exploitation in the next 30 days.

Description

Passing an attacker controlled size when creating an IOBuf could cause integer overflow, leading to an out of bounds write on the heap with the possibility of remote code execution. This issue affects versions of folly prior to v2021.07.22.00. This issue affects HHVM versions prior to 4.80.5, all versions between 4.81.0 and 4.102.1, all versions between 4.103.0 and 4.113.0, and versions 4.114.0, 4.115.0, 4.116.0, 4.117.0, 4.118.0 and 4.118.1.

Metrics

CVSS 3.1

9.8/10

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

EPSS Probability

3.28%

86.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Facebook	Folly	< 2021.07.22.00
Facebook	Hhvm	< 4.80.5
Facebook	Hhvm	>= 4.81.0, <= 4.102.1
Facebook	Hhvm	>= 4.103.0, <= 4.113.0
Facebook	Hhvm	4.114.0
Facebook	Hhvm	4.115.0
Facebook	Hhvm	4.116.0
Facebook	Hhvm	4.117.0
Facebook	Hhvm	4.118.0
Facebook	Hhvm	4.118.1

References

https://github.com/facebook/folly/commit/4f304af1411e68851bdd00ef6140e9de4616f7d3Patch, Third Party Advisory
https://hhvm.com/blog/2021/07/20/security-update.htmlProduct, Vendor Advisory
https://www.facebook.com/security/advisories/cve-2021-24036Vendor Advisory
https://github.com/facebook/folly/commit/4f304af1411e68851bdd00ef6140e9de4616f7d3Patch, Third Party Advisory
https://hhvm.com/blog/2021/07/20/security-update.htmlProduct, Vendor Advisory
https://www.facebook.com/security/advisories/cve-2021-24036Vendor Advisory

Timeline

Published: Jul 23, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-24036?

How severe is CVE-2021-24036?

CVE-2021-24036 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 3.28% probability of exploitation in the next 30 days.

How do I fix CVE-2021-24036?

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-2021-24036?

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

Scan your code now

Source: NVD / NIST