Cyber Resilience

CVE-2026-25520

Nyariv Sandboxjs ≤ 0.8.29

Public PoC
Published
06 February 2026
Modified
18 February 2026
Patch / advisory
View advisory
CVSS Score v3.1 10.0
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
EPSS Score 0.0078 53th percentile
Risk Priority 75 floored blend · peak EPSS

Summary

CVE-2026-25520 is a critical-severity Injection (CWE-74) vulnerability in Nyariv Sandboxjs. Its CVSS base score is 10.0 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked in the top 47% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

The strongest mitigations our analysis identified map to SI-10 (Information Input Validation) — see the control section below for these in your framework.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

CVE-2026-25520 is a critical vulnerability in SandboxJS, a JavaScript sandboxing library, affecting versions prior to 0.8.29. The issue arises because return values of functions are not properly wrapped, enabling the use of Object.values or Object.entries to obtain an array containing the host's Function constructor. Attackers can then leverage Array.prototype.at to access this constructor and execute arbitrary code outside the sandbox. The vulnerability is rated with a CVSS v3.1 base score of 10.0 (AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H) and is associated with CWE-74.

Any remote attacker can exploit this vulnerability without privileges or user interaction, as long as they can supply malicious JavaScript code to the sandboxed environment. Successful exploitation allows full sandbox escape, granting the attacker the ability to execute arbitrary code on the host system with the privileges of the process running SandboxJS, potentially leading to complete compromise of the affected application or server.

The vulnerability was addressed in SandboxJS version 0.8.29. Security advisories recommend updating to this patched version immediately. Details on the fix are provided in the GitHub security advisory at https://github.com/nyariv/SandboxJS/security/advisories/GHSA-58jh-xv4v-pcx4 and the fixing commit at https://github.com/nyariv/SandboxJS/commit/67cb186c41c78c51464f70405504e8ef0a6e43c3.

OWASP Top 10 for Web (2025)

A05:2025 Injection

EU & UK References

Vulnerability Data

SandboxJS is a JavaScript sandboxing library. Prior to 0.8.29, The return values of functions aren't wrapped. Object.values/Object.entries can be used to get an Array containing the host's Function constructor, by using Array.prototype.at you can obtain the hosts Function constructor, which…

more

can be used to execute arbitrary code outside of the sandbox. This vulnerability is fixed in 0.8.29.

CWE(s)
CWE-74

Related Threats

MITRE ATT&CK Enterprise Techniques

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 →
T1221 Template Injection Stealth
Adversaries may create or modify references in user document templates to conceal malicious code or force authentication attempts.
attack.mitre.org →
T1659 Content Injection Initial Access
Adversaries may gain access and continuously communicate with victims by injecting malicious content into systems through online network traffic.
attack.mitre.org →
T1674 Input Injection Execution
Adversaries may simulate keystrokes on a victim’s computer by various means to perform any type of action on behalf of the user, such as launching the command interpreter using keyboard shortcuts, typing an inline script to be executed,…
attack.mitre.org →
T1059 Command and Scripting Interpreter Execution
Adversaries may abuse command and script interpreters to execute commands, scripts, or binaries.
attack.mitre.org →
T1059.001 PowerShell Execution
Adversaries may abuse PowerShell commands and scripts for execution.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-25586Same product: Nyariv Sandboxjs
CVE-2023-23749Shared CWE-74
CVE-2023-48835Shared CWE-74
CVE-2023-51939Shared CWE-74
CVE-2023-33242Shared CWE-74
CVE-2023-4157Shared CWE-74
CVE-2024-28191Shared CWE-74
CVE-2022-2992Shared CWE-74
CVE-2023-44373Shared CWE-74
CVE-2020-9757Shared CWE-74

Affected Assets

nyariv
sandboxjs
≤ 0.8.29

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V1.2.1
  • V1.2.3
  • V1.2.5
  • V1.2.8

Mitigating Controls (NIST 800-53 r5) AI

SI-10 Information Input Validation good match

SI-10 directly requires validation of information inputs to reject malformed or special-element content before it reaches downstream parsers.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly require input validation and output encoding that prevent injection flaws.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing in development catches injection vulnerabilities before release.

A.8.15 Logging partial match
finds

Logging supports detection of injection attempts but does not prevent the weakness.

A.8.16 Monitoring activities partial match
finds

Monitoring activities can identify active injection attacks after they occur.

A.8.25 Secure development life cycle partial match
prevents

Secure development life cycle mandates input validation and output encoding that directly prevent injection flaws.

A.8.26 Application security requirements partial match
prevents

Application security requirements explicitly call for controls against injection attacks in software design.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure architecture principles reduce injection surfaces but do not prescribe specific neutralization techniques.

References