Cyber Posture

CVE-2026-0821

HighPublic PoC

Published: 10 January 2026

Published
10 January 2026
Modified
23 February 2026
KEV Added
Patch
CVSS Score 7.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
EPSS Score 0.0013 32.6th percentile
Risk Priority 15 60% EPSS · 20% KEV · 20% CVSS

Description

A vulnerability was determined in quickjs-ng quickjs up to 0.11.0. This vulnerability affects the function js_typed_array_constructor of the file quickjs.c. Executing a manipulation can lead to heap-based buffer overflow. The attack may be launched remotely. The exploit has been publicly…

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disclosed and may be utilized. This patch is called c5d80831e51e48a83eab16ea867be87f091783c5. A patch should be applied to remediate this issue.

Mitigating Controls (NIST 800-53 r5)AI

prevent

Requires timely identification, prioritization, and remediation of the heap-based buffer overflow flaw in quickjs via the specified patch.

prevent

Implements memory protection safeguards such as heap hardening and exploit mitigations to limit the impact of heap buffer overflow exploitation.

detect

Enables vulnerability scanning to identify systems running vulnerable versions of quickjs-ng up to 0.11.0.

Security SummaryAI

CVE-2026-0821 is a heap-based buffer overflow vulnerability in the quickjs-ng quickjs JavaScript engine, affecting versions up to 0.11.0. The issue resides in the js_typed_array_constructor function within the quickjs.c file and is associated with CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer) and CWE-122 (Heap-based Buffer Overflow). Published on 2026-01-10, it carries a CVSS v3.1 base score of 7.3 (High) with the vector AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L.

The vulnerability can be exploited remotely by unauthenticated attackers with low attack complexity and no user interaction required. Manipulation of the affected function triggers the heap-based buffer overflow, potentially allowing limited impacts to confidentiality, integrity, and availability. An exploit has been publicly disclosed and may be utilized by attackers.

Mitigation requires applying the patch at commit c5d80831e51e48a83eab16ea867be87f091783c5 in the quickjs-ng/quickjs repository. Further details are available in GitHub issue #1296, including comment #3780003395, and pull request #1299.

Details

CWE(s)

Affected Products

quickjs-ng
quickjs
≤ 0.11.0

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
Why these techniques?

Heap-based buffer overflow in QuickJS JavaScript engine exploitable remotely by unauthenticated attackers with no user interaction, directly enabling exploitation of public-facing applications.

Confidence: HIGH · MITRE ATT&CK Enterprise v19.0

References