CVE-2026-43898: SandboxJS is a JavaScript sandboxing library

This week

CRITICAL 10.0REMOTEUPGRADE

CVE-2026-43898 is a critical-severity flaw (CVSS 10.0) 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 0.9.6, sandbox-defined functions expose Function.caller, allowing sandboxed code to recover the internal LispType.Call runtime callback. That callback can then be invoked with attacker-controlled fake context and obj values to extract blocked host statics, recover the real host Function constructor, and execute arbitrary host JavaScript. This vulnerability is fixed in 0.9.6.

Why this priority

Critical severity
Public exploit reference
CISA SSVC: automatable with total technical impact
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	10.0 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.5% (top 59%)
CISA exploited list	No
Weakness	CWE-94
Published	2026-05-28
Last modified	2026-10-14

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

Last updated 2026-10-14 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-05-28 18:16 UTCPublished CVE record published
2026-10-14 20:10 UTCUpdated Record last modified

nyariv sandboxjs UPGRADE

Affected: < 0.9.6

Fixed in: 0.9.6

Safe to downgrade to: no unaffected older release

1. Check installed version

npm ls sandboxjs

2. UPGRADE to 0.9.6

npm install sandboxjs@">=0.9.6"

Exact fixes by distribution

npm · @nyariv/sandboxjs · FIXED · 0.9.6 · vulnerable: <= 0.9.5 · source

npm install @nyariv/sandboxjs@">=0.9.6" npm ls @nyariv/sandboxjs

Fedora 46 · fzssh · FIXED · 1.4.0-2.fc46 · FEDORA-2026-8004fcd067 · source

sudo dnf upgrade --advisory=FEDORA-2026-8004fcd067

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Write-up: github.com/nyariv/SandboxJS/security/advisories/GHSA-g8f2-4f4f-5jqw

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-2026-43898?

sandboxjs: upgrade to 0.9.6. Exact commands for each OS are on this page.

Is CVE-2026-43898 being exploited?

CVE-2026-43898 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-2026-43898 affect?

CVE-2026-43898 affects sandboxjs. Severity is critical (CVSS 10.0). SandboxJS is a JavaScript sandboxing library. Prior to 0.9.6, sandbox-defined functions expose Function.caller, allowing sandboxed code to recover the internal LispType.Call runtime callback. That callback can then be invoked with attacker-

How urgent is CVE-2026-43898?

Priority 58/100. Critical severity; Public exploit reference; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action

Related CVEs

CVE-2026-34208 CRITICAL 10.0 UPGRADE SandboxJS is a JavaScript sandboxing library
CVE-2026-34211 HIGH 7.5 UPGRADE SandboxJS is a JavaScript sandboxing library
CVE-2026-34217 HIGH 7.2 UPGRADE SandboxJS is a JavaScript sandboxing library

References

← Back to latest CVEs