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CVE-2019-19919· NVD / CVE Program· CNA mitre

Versions of handlebars prior to 4.3.0 are vulnerable to Prototype Pollution leading to Remote Code Execution.

Noroxi assessment

Priority: Plan (action score 41/100)

  • Public proof-of-concept code exists (GitHub); there is no record of exploitation in the wild.
  • Probability of exploitation in the next 30 days: 7% (FIRST EPSS); higher than 94.1% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: node-handlebars (Debian:12) 3:4.5.3-1; handlebars (npm) 4.3.0, 3.0.8.

Add it to your regular patch cycle. Upgrade to node-handlebars (Debian:12) 3:4.5.3-1; handlebars (npm) 4.3.0, 3.0.8 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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

CriticalCVSS 9.8 · v3.1—Proof of concept Fix available
Published
Dec 20, 2019
Updated
Jun 16, 2026
EPSS
7.0% · 94th percentile

Report tools

JSON

Action score

41

Plan

Add it to your regular patch cycle.

CVSS
39 / 40 · 9.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
2 / 30 · 7.0%

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • Proof of concept exists, no weaponized module
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2019-19919

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
handlebars.js projecthandlebars.js
tenabletenable.sc

Is the Handlebars on your site affected?

The free JavaScript library scanner reads the Handlebars version from the files your site loads, matches this record and other known vulnerabilities, and gives the safe version on the same branch. If the version can't be read, it says so. No account needed.

Scan JavaScript libraries

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • handlebars.js project handlebars.js1.0.10
  • handlebars.js project handlebars.js1.0.11
  • handlebars.js project handlebars.js1.0.12
  • handlebars.js project handlebars.js1.0.6
  • handlebars.js project handlebars.js1.0.7
  • handlebars.js project handlebars.js1.0.8
  • handlebars.js project handlebars.js1.0.9
  • handlebars.js project handlebars.js1.1.0
  • handlebars.js project handlebars.js1.1.1
  • handlebars.js project handlebars.js1.1.2
  • handlebars.js project handlebars.js1.2.0
  • handlebars.js project handlebars.js1.2.1
  • handlebars.js project handlebars.js1.3.0
  • handlebars.js project handlebars.js2.0.0
  • handlebars.js project handlebars.js3.0.0
  • handlebars.js project handlebars.js3.0.1
  • handlebars.js project handlebars.js3.0.2
  • handlebars.js project handlebars.js3.0.3
  • handlebars.js project handlebars.js3.0.4
  • handlebars.js project handlebars.js3.0.5

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12node-handlebarsbefore 3:4.5.3-13:4.5.3-1
npmhandlebarsfrom 4.0.0 · before 4.3.04.3.0
npmhandlebarsfrom 4.0.0 · before 4.3.04.3.0
npmhandlebarsbefore 3.0.83.0.8
npmhandlebarsbefore 3.0.83.0.8
RubyGemsbootstrap-wysihtml5-railsfrom 0.3.3.5 · up to and including 0.3.3.8—

Same product

handlebars.js project: all records

Other highest-scoring records for the same primary product.

  • CVE-2015-8861The handlebars package before 4.0.0 for Node.js allows remote attackers to conduct cross-site scripting (XSS) attacks by leveraging a templa
    25Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
debian:node-handlebars3:4.5.3-1 · Debian:12Package registry (OSV)
npm:handlebars3.0.8Package registry (OSV)
npm:handlebars4.3.0Package registry (OSV)

Exploit status

Proof of concept available

A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.

Evidence

  • Proof-of-concept repository on GitHub ×1

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
SourceKindDate
Proof-of-concept repository on GitHubstars:62024-10-19

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. Published
  2. First PoC+1764 d
  3. TodayOct 21, 2026+2497 d
EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

The product’s vendor appears in a public program. Matched by name; verify the scope text in the program.

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-1321 · Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (1 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records