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Prototype Pollution in handlebars

Critical severity GitHub Reviewed Published Dec 26, 2019 to the GitHub Advisory Database • Updated Feb 12, 2025

Package

bundler bootstrap-wysihtml5-rails (RubyGems)

Affected versions

>= 0.3.3.5, <= 0.3.3.8

Patched versions

None
npm handlebars (npm)
>= 4.0.0, < 4.3.0
< 3.0.8
4.3.0
3.0.8

Description

Versions of handlebars prior to 3.0.8 or 4.3.0 are vulnerable to Prototype Pollution leading to Remote Code Execution. Templates may alter an Objects' __proto__ and __defineGetter__ properties, which may allow an attacker to execute arbitrary code through crafted payloads.

Recommendation

Upgrade to version 3.0.8, 4.3.0 or later.

References

Published by the National Vulnerability Database Dec 20, 2019
Reviewed Dec 26, 2019
Published to the GitHub Advisory Database Dec 26, 2019
Last updated Feb 12, 2025

Severity

Critical

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(90th percentile)

Weaknesses

CVE ID

CVE-2019-19919

GHSA ID

GHSA-w457-6q6x-cgp9

Source code

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