CVE-2021-24036

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.

Published: 2021-07-23 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-24036 is rated High Risk (72/100): CVSS Critical severity, with high exploitation likelihood (EPSS 6.19%, 91th percentile). EPSS ranks this CVE among the most likely to be exploited in the near term. EPSS rose +1.08% over the last day, indicating growing attacker interest. High exploitation likelihood—assess exposure and prioritize remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-24036

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2025-12-28 5.10% 6.19% +1.08%
2 2025-12-27 6.19% 5.10% -1.08%
3 2025-10-28 — 6.19% —

Full EPSS history (23 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-24036

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]
7.5 2.0 HIGH
AV:N/AC:L/Au:N/C:P/I:P/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 6.4 [email protected]

Weakness enumeration for CVE-2021-24036

OS Trackers for CVE-2021-24036

vendor priority summary link
ubuntu medium CVE-2021-24036 medium priority: Ubuntu including 1 source packages (hhvm), 15 status rows across 15 suites (bionic, focal, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): DNE 12, needs-triage 3. https://ubuntu.com/security/CVE-2021-24036

Affected software / configurations for CVE-2021-24036

Vendor Product Version Raw CPE
facebook folly < 2021.07.22.00 cpe:2.3:a:facebook:folly:*:*:*:*:*:*:*:*
facebook hhvm < 4.80.5 cpe:2.3:a:facebook:hhvm:*:*:*:*:*:*:*:*
facebook hhvm >= 4.81.0, <= 4.102.1 cpe:2.3:a:facebook:hhvm:*:*:*:*:*:*:*:*
facebook hhvm >= 4.103.0, <= 4.113.0 cpe:2.3:a:facebook:hhvm:*:*:*:*:*:*:*:*
facebook hhvm 4.114.0 cpe:2.3:a:facebook:hhvm:4.114.0:*:*:*:*:*:*:*
facebook hhvm 4.115.0 cpe:2.3:a:facebook:hhvm:4.115.0:*:*:*:*:*:*:*
facebook hhvm 4.116.0 cpe:2.3:a:facebook:hhvm:4.116.0:*:*:*:*:*:*:*
facebook hhvm 4.117.0 cpe:2.3:a:facebook:hhvm:4.117.0:*:*:*:*:*:*:*
facebook hhvm 4.118.0 cpe:2.3:a:facebook:hhvm:4.118.0:*:*:*:*:*:*:*
facebook hhvm 4.118.1 cpe:2.3:a:facebook:hhvm:4.118.1:*:*:*:*:*:*:*

References for CVE-2021-24036

cvelogic Threat Intelligence