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High

Prototype Pollution in handlebars

  • Disclosed: 05.06.2019
  • Updated: 11.10.2026 10:22

Versions of handlebars prior to 4.0.14 are vulnerable to Prototype Pollution. Templates may alter an Objects' prototype, thus allowing an attacker to execute arbitrary code on the server.

Recommendation

For handlebars 4.1.x upgrade to 4.1.2 or later. For handlebars 4.0.x upgrade to 4.0.14 or later.

Affected software

Click a technology to see all vulnerabilities affecting it.

PlatformPackageVulnerable versionsFixed in
npm package handlebars >= 4.1.0, < 4.1.2, >= 4.0.0, < 4.0.14, < 3.0.7 4.1.2, 4.0.14, 3.0.7

References

CVSS score 7.3/10
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
Weakness (CWE)
CWE-471
Platform
npm
Package
handlebars
Disclosed
05.06.2019
Updated
11.10.2026 10:22

Sources and licenses

OSV / GitHub Advisory Database - GHSA-q42p-pg8m-cqh6 - CC BY 4.0

Vulnerability history: handlebars

All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.

All (22) in the archive
Total entries
22
First → latest
10.2018 10.2026
Without a fix
0
Exploited in attacks
0

Severity breakdown

  • Critical 6
  • High 10
  • Medium 5
  • Low 1

Disclosures per year

Severity:
  1. Handlebars: JavaScript Injection via AST Type Confusion in compile (bypass of CVE-2026-33937)
    Critical · 9.8 CVE-2026-106446 >= 4.0.0, < 4.7.10 4.7.10
  2. Handlebars: JavaScript Injection via Own Property Check Bypass
    Critical CVE-2026-106445 >= 3.0.0, < 4.7.10 4.7.10
  3. Handlebars.js has JavaScript Injection in CLI Precompiler via Unescaped Names and Options
    High · 8.2 CVE-2026-33941 >= 4.0.0, < 4.7.9 4.7.9
  4. Handlebars.js has JavaScript Injection via AST Type Confusion when passing an object as dynamic partial
    High · 8.1 CVE-2026-33940 >= 4.0.0, < 4.7.9 4.7.9
  5. Handlebars.js has Denial of Service via Malformed Decorator Syntax in Template Compilation
    High · 7.5 CVE-2026-33939 >= 4.0.0, < 4.7.9 4.7.9
  6. Handlebars.js has JavaScript Injection via AST Type Confusion by tampering @partial-block
    High · 8.1 CVE-2026-33938 >= 4.0.0, < 4.7.9 4.7.9
  7. Handlebars.js has JavaScript Injection via AST Type Confusion
    Critical · 9.8 CVE-2026-33937 >= 4.0.0, < 4.7.9 4.7.9
  8. Prototype Pollution in handlebars
    Critical · 9.8 CVE-2021-23383 < 4.7.7 4.7.7
  9. Regular Expression Denial of Service in Handlebars
    High · 7.5 CVE-2019-20922 >= 4.0.0, < 4.4.5 4.4.5
  10. Arbitrary Code Execution in Handlebars
    High · 8.1 CVE-2019-20920 < 3.0.8, >= 4.0.0, < 4.5.3 3.0.8, 4.5.3
  11. Remote code execution in handlebars when compiling templates
    Critical · 9.8 CVE-2021-23369 < 4.7.7 4.7.7
  12. Arbitrary Code Execution in handlebars
    High ghsa-q2c6-c6pm-g3gh < 3.0.8, >= 4.0.0, < 4.5.3 3.0.8, 4.5.3
  13. Prototype Pollution in handlebars
    High ghsa-g9r4-xpmj-mj65 < 3.0.8, >= 4.0.0, < 4.5.3 3.0.8, 4.5.3
  14. Arbitrary Code Execution in handlebars
    High · 7.3 ghsa-2cf5-4w76-r9qv < 3.0.8, >= 4.0.0, < 4.5.2 3.0.8, 4.5.2
  15. Prototype Pollution in handlebars
    Critical · 9.8 CVE-2019-19919 >= 4.0.0, < 4.3.0, < 3.0.8 4.3.0, 3.0.8
  16. Prototype Pollution in handlebars this entry
    High · 7.3 ghsa-q42p-pg8m-cqh6 >= 4.1.0, < 4.1.2, >= 4.0.0, < 4.0.14, < 3.0.7 4.1.2, 4.0.14, 3.0.7

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