Cyber Resilience

CVE-2026-53609

Critical

Published: 12 June 2026

Published
12 June 2026
Modified
17 June 2026
KEV Added
—
Patch
—
CVSS Score v3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:L
EPSS Score 0.0024 14.7th percentile
Risk Priority 70 floored blend · peak EPSS

Summary

CVE-2026-53609 is a critical-severity Prototype Pollution (CWE-1321) vulnerability. Its CVSS base score is 9.1 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 14.7th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

EU & UK References

Vulnerability details

ApostropheCMS is an open-source Node.js content management system. In versions up to and including 4.30.0, `apos.util.set()` traverses dot-notation paths without sanitizing `__proto__`, allowing an authenticated editor to write arbitrary values to `Object.prototype` via the `$pullAll` patch operator. A confirmed gadget…

more

in `publicApiCheck()` causes this to bypass authorization on all piece-type REST API endpoints for every subsequent unauthenticated request, for the lifetime of the Node.js process. As of time of publication, no known patched versions are available.

CWE(s)
CWE-1321

Related Threats

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.
attack.mitre.org →
Why these techniques?

Prototype pollution enables auth bypass on public REST API endpoints of the CMS, directly facilitating exploitation of a public-facing application.

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

Affected Assets

—
In
inferred from references and description; NVD did not file a CPE for this CVE

Mitigating Controls

No mitigating controls mapped yet. The per-CVE control annotator has not reached this CVE.

References