Reference page — cumulative record through Sunday, October 4, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.
CVE-2026-33937
handlebars-lang handlebars.js — Handlebars.js has JavaScript Injection via AST Type Confusion
AV AC PR UI S C I A CVSS EPSS %ile KEV
N L N N U H H H 9.8 .0174 76.9 —
AFFECTED
Product Versions Fixed
handlebars.js >= 4.0.0, < 4.7.9 – —
TIMELINE
Mar 24 Reserved by GitHub_M
Mar 27 Published (CNA: GitHub_M)
Aug 31 EXPLOIT PUBLISHED — CVE-2026-33937 (handlebars-lang handlebars.js). Public exploit reference added.
Sep 4 EXPLOIT PUBLISHED — CVE-2026-33937 (handlebars-lang handlebars.js). Public exploit reference added.
Description
Handlebars provides the power necessary to let users build semantic templates. In versions 4.0.0 through 4.7.8, `Handlebars.compile()` accepts a pre-parsed AST object in addition to a template string. The `value` field of a `NumberLiteral` AST node is emitted directly into the generated JavaScript without quoting or sanitization. An attacker who can supply a crafted AST to `compile()` can therefore inject and execute arbitrary JavaScript, leading to Remote Code Execution on the server. Version 4.7.9 fixes the issue. Some workarounds are available. Validate input type before calling `Handlebars.compile()`; ensure the argument is always a `string`, never a plain object or JSON-deserialized value. Use the Handlebars runtime-only build (`handlebars/runtime`) on the server if templates are pre-compiled at build time; `compile()` will be unavailable.
Lifecycle
Complete event history — 4 events, chronological
| Date | Event | Detail |
|---|
| March 24, 2026 | Reserved | Reserved by GitHub_M |
| March 27, 2026 | Published | Published (CNA: GitHub_M) |
| August 31, 2026 | EXPLOIT PUBLISHED | EXPLOIT PUBLISHED — CVE-2026-33937 (handlebars-lang handlebars.js). Public exploit reference added. |
| September 4, 2026 | EXPLOIT PUBLISHED | EXPLOIT PUBLISHED — CVE-2026-33937 (handlebars-lang handlebars.js). Public exploit reference added. |
Affected
Affected products and packages — 1 row
| Vendor | Product / Package | Ecosystem | Version introduced | Fixed |
|---|
| handlebars-lang | handlebars.js | — | >= 4.0.0, < 4.7.9 | — |
About this page
This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2026-33937 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Sunday, October 4, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.
