CVE-2026-34211: SandboxJS is a JavaScript sandboxing library

This week

HIGH 7.5REMOTEUPGRADE

CVE-2026-34211 is a high-severity flaw (CVSS 7.5) affecting sandboxjs. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

SandboxJS is a JavaScript sandboxing library. Prior to 0.8.36, the @nyariv/sandboxjs parser contains unbounded recursion in the restOfExp function and the lispify/lispifyExpr call chain. An attacker can crash any Node.js process that parses untrusted input by supplying deeply nested expressions (e.g., ~2000 nested parentheses), causing a RangeError: Maximum call stack size exceeded that terminates the process. This vulnerability is fixed in 0.8.3

Why this priority

High severity
Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.4% (top 67%)
CISA exploited list	No
Weakness	CWE-674
Published	2026-04-06
Last modified	2026-10-26

Publisher (CNA): GitHub, Inc. · Vendor: nyariv

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-06 16:16 UTCPublished CVE record published
2026-10-26 22:10 UTCUpdated Record last modified

nyariv sandboxjs UPGRADE

Affected: < 0.8.36

Fixed in: 0.8.36

Safe to downgrade to: no unaffected older release

1. Check installed version

npm ls sandboxjs

2. UPGRADE to 0.8.36

npm install sandboxjs@">=0.8.36"

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-34211?

sandboxjs: upgrade to 0.8.36. Exact commands for each OS are on this page.

Is CVE-2026-34211 being exploited?

CVE-2026-34211 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-34211 affect?

CVE-2026-34211 affects sandboxjs. Severity is high (CVSS 7.5). SandboxJS is a JavaScript sandboxing library. Prior to 0.8.36, the @nyariv/sandboxjs parser contains unbounded recursion in the restOfExp function and the lispify/lispifyExpr call chain. An attacker can crash any Node.js process that parses

How urgent is CVE-2026-34211?

Priority 45/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

Software pages

Node.js vulnerabilities

Related CVEs

CVE-2026-34208 CRITICAL 10.0 UPGRADE SandboxJS is a JavaScript sandboxing library
CVE-2026-34217 HIGH 7.2 UPGRADE SandboxJS is a JavaScript sandboxing library

References

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