CVE-2026-34208
SandboxJS pre-0.8.36 sandbox bypass allows mutating host globals.
Is CVE-2026-34208 being exploited?
Not confirmed. CVE-2026-34208 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.56% probability of exploitation in the next 30 days.
How severe is CVE-2026-34208?
CVE-2026-34208 is rated Critical with a CVSS score of 10.0. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-34208?
Yes. A fix has been recorded for CVE-2026-34208. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-34208 affect?
CVE-2026-34208 affects SandboxJS. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-34208?
Upgrade to 0.8.36 or newer.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Attacker can write arbitrary properties to host global objects via the exposed constructor path, persisting across sandboxes.
Patch when possible
- affected< 0.8.36
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.