CVE-2026-33916

Publication date 30 March 2026

Last updated 30 March 2026

Ubuntu priority

Medium

Why this priority?

Cvss 3 Severity Score

4.7 · Medium

Score breakdown

Description

Handlebars provides the power necessary to let users build semantic templates. In versions 4.0.0 through 4.7.8, `resolvePartial()` in the Handlebars runtime resolves partial names via a plain property lookup on `options.partials` without guarding against prototype-chain traversal. When `Object.prototype` has been polluted with a string value whose key matches a partial reference in a template, the polluted string is used as the partial body and rendered without HTML escaping, resulting in reflected or stored XSS. Version 4.7.9 fixes the issue. Some workarounds are available. Apply `Object.freeze(Object.prototype)` early in application startup to prevent prototype pollution. Note: this may break other libraries, and/or use the Handlebars runtime-only build (`handlebars/runtime`), which does not compile templates and reduces the attack surface.

Status

Package Ubuntu Release Status
node-handlebars 25.10 questing
Needs evaluation
24.04 LTS noble
Needs evaluation
22.04 LTS jammy
Needs evaluation
20.04 LTS focal
Needs evaluation
18.04 LTS bionic
Needs evaluation

Severity score breakdown

Parameter Value
Base score 4.7 · Medium
Attack vector Network
Attack complexity High
Privileges required None
User interaction Required
Scope Changed
Confidentiality Low
Integrity impact Low
Availability impact None
Vector CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N

References

Other references

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