HOMEVULNERABILITIESCVE-2021-24036
CRITICAL

CVE-2021-24036

CWE-122Published: July 23, 2021· Updated: Jun 17, 2026

9.8
CVSS v3.1

Official 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.

NVD Source

Technical Analysis

CVE-2021-24036 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 9.8.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected Vendors & Products

facebook2 product(s)
follyhhvm
Source: NVD CPE · 8 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

PATCHhttps://github.com/facebook/folly/commit/4f304af1411e68851bdd00ef6140e9de4616f7d3
PATCHhttps://github.com/facebook/folly/commit/4f304af1411e68851bdd00ef6140e9de4616f7d3
ADVISORYhttps://hhvm.com/blog/2021/07/20/security-update.html
ADVISORYhttps://www.facebook.com/security/advisories/cve-2021-24036
ADVISORYhttps://hhvm.com/blog/2021/07/20/security-update.html
ADVISORYhttps://www.facebook.com/security/advisories/cve-2021-24036

All References (6)

→
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

Quick Facts

CVE IDCVE-2021-24036
CVSS Score9.8 / 10
SeverityCRITICAL
WeaknessCWE-122
CISA KEVNo
Affected1 vendor(s)
PublishedJul 23, 2021

Related CVEs (CWE-122)

CVE-2021-25387
10.0
CVE-2022-34819
10.0
CVE-2026-46752
10.0
CVE-2025-23123
10.0
CVE-2021-21940
10.0
CVE-2026-44050
9.9

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2021-24036 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.
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