Handlebars is widely used for server-side templating; this flaw allows attacker-controlled templates to achieve server-side RCE, risking widespread data and system compromise.
CVE-2026-106445
Handlebars <4.7.10 prototype bypass enables server-side RCE
Is CVE-2026-106445 being exploited?
Not confirmed. CVE-2026-106445 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 0.41% probability of exploitation in the next 30 days.
How severe is CVE-2026-106445?
CVE-2026-106445 is rated Critical with a CVSS score of 9.2. 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-2026-106445?
Yes. A fix has been recorded for CVE-2026-106445. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-106445 affect?
CVE-2026-106445 affects Handlebars.js <= 4.7.9, Web apps using server-side Handlebars with allowProtoMethodsByDefault. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-106445?
Upgrade to v4.7.10; disable allowProtoMethodsByDefault; audit templates.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote arbitrary JavaScript execution as the server process via crafted templates when allowProtoMethodsByDefault is enabled.
Immediate action required
- affected>= 4.0.0 and < 4.7.10
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.