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CVE-2021-43453

31
FAUCET Score

CVE-2021-43453 is a critical heap-based buffer overflow vulnerability affecting JerryScript 2.4.0 and earlier versions, specifically due to an out-of-bounds read in the parser_parse_for_statement_start function. With a CVSS score of 9.8, it allows for unauthenticated remote attackers to achieve high confidentiality, integrity, and availability impacts with low attack complexity. While there is no evidence of active exploitation, public exploit code, or inclusion in CISA's KEV catalog, the vulnerability has garnered significant community discussion, indicating awareness among security researchers.

Impacted Technologies

VendorProductVersion(s)CPE
<= 2.4.0CPE matchmatch criteria
cpe:2.3:a:jerryscript:jerryscript:*:*:*:*:*:*:*:*

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
1.24%
Probability of exploitation in next 30 days
EPSS Percentile
66.0%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0124 is in the 52nd percentile among its peer group of 36,897 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

Remediation records are not available for this CVE.

References

github.com / jerryscript-project/jerryscript/issues/4754
ExploitIssue TrackingThird Party Advisory