CVE-2021-44994Public exploit

Engine crash via negative-zero Atomics index

Published Jan 25, 2022 · Updated Aug 4, 2024

Reachable assertion in JerryScript 3.0.0 allows context-dependent attackers to crash the engine by executing crafted JavaScript. The public reproducer calls Atomics.add on a SharedArrayBuffer-backed Int32Array with negative zero, leaving allocated heap state when jmem_heap_finalize checks that it is zero. Reachability requires execution of attacker-supplied script in an assertion-enabled build with SharedArrayBuffer and Atomics support; the demonstrated consequence is engine termination.

CVSS severity5.5
Medium
EPSS probability1.02%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reachable assertion in JerryScript 3.0.0 allows context-dependent attackers to crash the engine by executing crafted JavaScript. The public reproducer calls Atomics.add on a SharedArrayBuffer-backed Int32Array with negative zero, leaving allocated heap state when jmem_heap_finalize checks that it is zero. Reachability requires execution of attacker-supplied script in an assertion-enabled build with SharedArrayBuffer and Atomics support; the demonstrated consequence is engine termination.

The record

CVE
CVE-2021-44994
Published
Jan 25, 2022
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-617
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 25, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:N/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-617Reachable Assertion

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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