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Public proof of conceptFix available

CVE-2019-19919

A public proof of concept exists; no exploitation attested.

  • Published2019-12-20
  • WeaknessCWE-1321

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

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.

Timeline

dates in UTC
  1. 2019-12-2023:15CVE publishedNVD
  2. 2026-10-2319:23First public proof of conceptPoC-in-GitHub

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2019-19919?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2019-19919?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD · OSV
Handlebars.js project handlebars.js
BranchAffectedFixed in
1.0= 1.0.6no fix published
1.0= 1.0.7no fix published
1.0= 1.0.8no fix published
1.0= 1.0.9no fix published
1.0= 1.0.10no fix published
1.0= 1.0.11no fix published
1.0= 1.0.12no fix published
1.1= 1.1.0no fix published
1.1= 1.1.1no fix published
1.1= 1.1.2no fix published
1.2= 1.2.0no fix published
1.2= 1.2.1no fix published
handlebars
BranchAffectedFixed in
4.x≥ 4.0.0, < 4.3.04.3.0
3.0< 3.0.83.0.8
Tenable tenable.sc
BranchAffectedFixed in
5.19< 5.19.05.19.0

1 more product in the sources.

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Advisories and patches

Detection

read 2026-10-23 19:23 UTC
Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
1 repository, unverifiedfazilbaig1/CVE-2019-19919
PoC-in-GitHub

Sources

  • NVDCVSS 3.19.8read 2026-10-23
  • NVDCVSS 2.07.5read 2026-10-23
  • NVDweakness (CWE)CWE-1321read 2026-10-23
  • FIRST EPSSEPSS score7.1 %2026-10-22
  • PoC-in-GitHubproof of concept1read 2026-10-23
  • OSVaffected packages—

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published
2019-12-20
Last Modified
2026-06-17
NVD status
Modified

Frequently asked questions

What is CVE-2019-19919?

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.

Is CVE-2019-19919 actively exploited?

Active exploitation of CVE-2019-19919 has not been confirmed. Its EPSS score was 7.1% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2019-19919?

CVE-2019-19919 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

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