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CVE-2021-24037

29
FAUCET Score

CVE-2021-24037 describes a critical use-after-free vulnerability in Facebook's Hermes JavaScript engine, specifically when emitting certain error messages. This flaw, present before commit d86e185e485b6330216dee8e854455c694e3a36e, could allow attackers to execute arbitrary code through crafted JavaScript. With a CVSS score of 9.8 (CRITICAL), it presents a high-impact threat (confidentiality, integrity, availability) with a network attack vector and low attack complexity, though it primarily affects applications permitting untrusted JavaScript evaluation, largely excluding typical React Native apps. Currently, there is no evidence of active exploitation, public exploit code, or significant community discussion, and it is not listed in CISA's KEV catalog.

Impacted Technologies

VendorProductVersion(s)CPE
< 0.8.0CPE matchmatch criteria
cpe:2.3:a:facebook:hermes:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

9.8CRITICAL

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.80%
Probability of exploitation in next 30 days
EPSS Percentile
76.1%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0180 is in the 64th percentile among its peer group of 36,862 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

github_advisorypatch availablevia nvd_reference
View patch
npmpatch availablevia ghsa
Product: hermes-engineFixed in: 0.8.0

Vendor Advisories (1)

npmGHSA-mph8-6787-r8hwcritical

Use After Free in Hermes

May 24, 2022

References

github.com / facebook/hermes/commit/d86e185e485b6330216dee8e854455c694e3a36e
PatchThird Party Advisory
facebook.com / security/advisories/CVE-2021-24037
Vendor Advisory