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CVE-2019-19919

Arbitrary Code Execution in handlebars

9.8 CriticalPublic exploitFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
High

Exploit likelihood

7.07%Up 6.1 points since Apr 14, 2021
90%50%10%1%

What each source reports

NVD Score used 9.8

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.

Record
CVE-2019-19919
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS 2.0
7.5 HighAV:N/AC:L/Au:N/C:P/I:P/A:P
Weakness
CWE-1321
Updated
2026-11-02
CVE List No score

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.

Record
CVE-2019-19919
Updated
2026-11-02
EUVDEUVD-2019-0803 No score

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.

Record
EUVD-2019-0803
Updated
2026-11-03
GitHub AdvisoriesGHSA-2cf5-4w76-r9qv 7.3

Arbitrary Code Execution in handlebars

Versions of handlebars prior to 3.0.8 or 4.5.2 are vulnerable to Arbitrary Code Execution. The package's lookup helper fails to properly validate templates, allowing attackers to submit templates that execute arbitrary JavaScript in the system. It can be used to run arbitrary code in a server processing Handlebars templates or on a victim's browser (effectively serving as Cross-Site Scripting).

The following template can be used to demonstrate the vulnerability:

	{{#with split as |a|}}
		{{pop (push "alert('Vulnerable Handlebars JS');")}}
		{{#with (concat (lookup join (slice 0 1)))}}
			{{#each (slice 2 3)}}
				{{#with (apply 0 a)}}
					{{.}}
				{{/with}}
			{{/each}}
		{{/with}}
	{{/with}}
{{/with}}```


## Recommendation

Upgrade to version 3.0.8, 4.5.2 or later.
Record
GHSA-2cf5-4w76-r9qv
CVSS 3.1
7.3 HighCVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:C/C:L/I:H/A:L
Weakness
CWE-94
Updated
2026-11-02
GitHub AdvisoriesGHSA-q42p-pg8m-cqh6 7.3

Prototype Pollution in handlebars

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.

Record
GHSA-q42p-pg8m-cqh6
CVSS 3.1
7.3 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
Weakness
CWE-471
Updated
2026-11-02
GitHub AdvisoriesGHSA-w457-6q6x-cgp9 9.8

Prototype Pollution in handlebars

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.

Record
GHSA-w457-6q6x-cgp9
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-74, CWE-1321
Updated
2026-11-02
Show 22 moreShow less
GitHub AdvisoriesGHSA-g9r4-xpmj-mj65 No score

Prototype Pollution in handlebars

Versions of handlebars prior to 3.0.8 or 4.5.3 are vulnerable to prototype pollution. It is possible to add or modify properties to the Object prototype through a malicious template. This may allow attackers to crash the application or execute Arbitrary Code in specific conditions.

Recommendation

Upgrade to version 3.0.8, 4.5.3 or later.

Record
GHSA-g9r4-xpmj-mj65
Weakness
CWE-1321
Updated
2026-11-02
GitHub AdvisoriesGHSA-q2c6-c6pm-g3gh No score

Arbitrary Code Execution in handlebars

Versions of handlebars prior to 3.0.8 or 4.5.3 are vulnerable to Arbitrary Code Execution. The package's lookup helper fails to properly validate templates, allowing attackers to submit templates that execute arbitrary JavaScript in the system. It is due to an incomplete fix for a previous issue. This vulnerability can be used to run arbitrary code in a server processing Handlebars templates or on a victim's browser (effectively serving as Cross-Site Scripting).

Recommendation

Upgrade to version 3.0.8, 4.5.3 or later.

Record
GHSA-q2c6-c6pm-g3gh
Updated
2026-11-02
OSV 9.8

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.

Record
CVE-2019-19919
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVDEBIAN-CVE-2019-19919 9.8

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.

Record
DEBIAN-CVE-2019-19919
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVGHSA-2cf5-4w76-r9qv 7.3

Arbitrary Code Execution in handlebars

Versions of handlebars prior to 3.0.8 or 4.5.2 are vulnerable to Arbitrary Code Execution. The package's lookup helper fails to properly validate templates, allowing attackers to submit templates that execute arbitrary JavaScript in the system. It can be used to run arbitrary code in a server processing Handlebars templates or on a victim's browser (effectively serving as Cross-Site Scripting).

The following template can be used to demonstrate the vulnerability:

	{{#with split as |a|}}
		{{pop (push "alert('Vulnerable Handlebars JS');")}}
		{{#with (concat (lookup join (slice 0 1)))}}
			{{#each (slice 2 3)}}
				{{#with (apply 0 a)}}
					{{.}}
				{{/with}}
			{{/each}}
		{{/with}}
	{{/with}}
{{/with}}```


## Recommendation

Upgrade to version 3.0.8, 4.5.2 or later.
Record
GHSA-2cf5-4w76-r9qv
CVSS 3.1
7.3 HighCVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:C/C:L/I:H/A:L
Weakness
CWE-94
Updated
2026-11-02
OSVGHSA-q42p-pg8m-cqh6 7.3

Prototype Pollution in handlebars

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.

Record
GHSA-q42p-pg8m-cqh6
CVSS 3.1
7.3 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
Weakness
CWE-471
Updated
2026-11-02
OSVGHSA-w457-6q6x-cgp9 9.8

Prototype Pollution in handlebars

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.

Record
GHSA-w457-6q6x-cgp9
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-1321, CWE-74
Updated
2026-11-02
OSVUBUNTU-CVE-2019-19919 9.8

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.

Record
UBUNTU-CVE-2019-19919
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVCLSA-2026-1773101681 No score

TuxCare security update for handlebars (9 CVEs)

TuxCare rebuilt handlebars to address 9 CVEs. Fixed in 3.0.3-tuxcare.1.

Record
CLSA-2026-1773101681
Updated
2026-11-02
OSVCLSA-2026-1774743817 No score

TuxCare security update for handlebars (1 CVE)

TuxCare rebuilt handlebars to address 1 CVE. Fixed in 1.3.0-tuxcare.1.

Record
CLSA-2026-1774743817
Updated
2026-11-02
OSVCLSA-2026-1774743830 No score

TuxCare security update for handlebars (3 CVEs)

TuxCare rebuilt handlebars to address 3 CVEs. Fixed in 1.0.12-tuxcare.2.

Record
CLSA-2026-1774743830
Updated
2026-11-02
OSVCLSA-2026-1774743831 No score

TuxCare security update for handlebars (2 CVEs)

TuxCare rebuilt handlebars to address 2 CVEs. Fixed in 1.3.0-tuxcare.2.

Record
CLSA-2026-1774743831
Updated
2026-11-02
OSVCLSA-2026-1774743832 No score

TuxCare security update for handlebars (2 CVEs)

TuxCare rebuilt handlebars to address 2 CVEs. Fixed in 2.0.0-tuxcare.2.

Record
CLSA-2026-1774743832
Updated
2026-11-02
OSVCLSA-2026-1776991069 No score

TuxCare security update for handlebars (9 CVEs)

TuxCare rebuilt handlebars to address 9 CVEs. Fixed in 4.7.9-tuxcare.1.

Record
CLSA-2026-1776991069
Updated
2026-11-02
OSVCLSA-2026-1786731948 No score

TuxCare security update for dompurify (34 CVEs)

TuxCare rebuilt dompurify to address 34 CVEs. Fixed in 3.0.3-tuxcare.1.

Record
CLSA-2026-1786731948
Updated
2026-11-02
OSVGHSA-g9r4-xpmj-mj65 No score

Prototype Pollution in handlebars

Versions of handlebars prior to 3.0.8 or 4.5.3 are vulnerable to prototype pollution. It is possible to add or modify properties to the Object prototype through a malicious template. This may allow attackers to crash the application or execute Arbitrary Code in specific conditions.

Recommendation

Upgrade to version 3.0.8, 4.5.3 or later.

Record
GHSA-g9r4-xpmj-mj65
Weakness
CWE-1321
Updated
2026-11-02
OSVGHSA-q2c6-c6pm-g3gh No score

Arbitrary Code Execution in handlebars

Versions of handlebars prior to 3.0.8 or 4.5.3 are vulnerable to Arbitrary Code Execution. The package's lookup helper fails to properly validate templates, allowing attackers to submit templates that execute arbitrary JavaScript in the system. It is due to an incomplete fix for a previous issue. This vulnerability can be used to run arbitrary code in a server processing Handlebars templates or on a victim's browser (effectively serving as Cross-Site Scripting).

Recommendation

Upgrade to version 3.0.8, 4.5.3 or later.

Record
GHSA-q2c6-c6pm-g3gh
Updated
2026-11-02
OSVROOT-APP-NPM-CVE-2019-19919 No score

CVE-2019-19919 in handlebars - Patched by Root

Root has patched CVE-2019-19919 in the handlebars package for Root:npm. Multiple fixed versions available.

Record
ROOT-APP-NPM-CVE-2019-19919
Updated
2026-11-02
OSVROOT-APP-NPM-GHSA-2cf5-4w76-r9qv No score

GHSA-2cf5-4w76-r9qv in handlebars - Patched by Root

Root has patched GHSA-2cf5-4w76-r9qv in the handlebars package for Root:npm. Multiple fixed versions available.

Record
ROOT-APP-NPM-GHSA-2cf5-4w76-r9qv
Updated
2026-11-02
OSVROOT-APP-NPM-GHSA-g9r4-xpmj-mj65 No score

GHSA-g9r4-xpmj-mj65 in handlebars - Patched by Root

Root has patched GHSA-g9r4-xpmj-mj65 in the handlebars package for Root:npm. Multiple fixed versions available.

Record
ROOT-APP-NPM-GHSA-g9r4-xpmj-mj65
Updated
2026-11-02
OSVROOT-APP-NPM-GHSA-q2c6-c6pm-g3gh No score

GHSA-q2c6-c6pm-g3gh in handlebars - Patched by Root

Root has patched GHSA-q2c6-c6pm-g3gh in the handlebars package for Root:npm. Multiple fixed versions available.

Record
ROOT-APP-NPM-GHSA-q2c6-c6pm-g3gh
Updated
2026-11-02
OSVROOT-APP-NPM-GHSA-q42p-pg8m-cqh6 No score

GHSA-q42p-pg8m-cqh6 in handlebars - Patched by Root

Root has patched GHSA-q42p-pg8m-cqh6 in the handlebars package for Root:npm. Multiple fixed versions available.

Record
ROOT-APP-NPM-GHSA-q42p-pg8m-cqh6
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
handlebars
npm
before 3.0.8
3.0.8
handlebars
npm
4.0.0 up to 4.5.2
4.5.2
handlebars
npm
4.0.0 up to 4.5.3
4.5.3
handlebars
npm
4.1.0 up to 4.1.2
4.1.2
handlebars
npm
4.0.0 up to 4.0.14
4.0.14
handlebars
npm
before 3.0.7
3.0.7
handlebars
npm
4.0.0 up to 4.3.0
4.3.0
bootstrap-wysihtml5-rails
RubyGems
0.3.3.5 to 0.3.3.8 None known
handlebars
TuxCare:npm
From an advisory covering 5 CVEs
3.0.3-tuxcare.0 up to 3.0.3-tuxcare.1, plus listed versions
3.0.3
3.0.3-tuxcare.1
handlebars
TuxCare:npm
1.3.0-tuxcare.0 up to 1.3.0-tuxcare.1, plus listed versions
1.3.0
1.3.0-tuxcare.1
Show 13 moreShow less
Affected packages
PackageAffectedFixed
handlebars
TuxCare:npm
1.0.12-tuxcare.0 up to 1.0.12-tuxcare.2, plus listed versions
1.0.121.0.12-tuxcare.1
1.0.12-tuxcare.2
handlebars
TuxCare:npm
From an advisory covering 2 CVEs
1.3.0-tuxcare.0 up to 1.3.0-tuxcare.2, plus listed versions
1.3.01.3.0-tuxcare.1
1.3.0-tuxcare.2
handlebars
TuxCare:npm
From an advisory covering 2 CVEs
2.0.0-tuxcare.0 up to 2.0.0-tuxcare.2, plus listed versions
2.0.02.0.0-tuxcare.1
2.0.0-tuxcare.2
handlebars
TuxCare:npm
From an advisory covering 5 CVEs
4.7.9-tuxcare.0 up to 4.7.9-tuxcare.1, plus listed versions
4.7.9
4.7.9-tuxcare.1
node-handlebars
Debian:12
before 3:4.5.3-1
3:4.5.3-1
node-handlebars
Debian:13
before 3:4.5.3-1
3:4.5.3-1
node-handlebars
Debian:14
before 3:4.5.3-1
3:4.5.3-1
bootstrap-wysihtml5-rails
RubyGems
0.3.3.5 to 0.3.3.8, plus listed versions
0.3.3.60.3.3.7
None known
handlebars
Root:npm
before 3.0.7-aikido.3
3.0.7-aikido.33.0.3-aikido.23.0.8-aikido.13.0.8-aikido.2
@rootio/handlebars
Root:npm
before 3.0.7-root.io.3
3.0.7-root.io.33.0.3-root.io.23.0.8-root.io.13.0.8-root.io.2
handlebars
Root:npm
before 3.0.3-aikido.2
3.0.3-aikido.23.0.7-aikido.13.0.7-aikido.23.0.7-aikido.3
@rootio/handlebars
Root:npm
before 3.0.3-root.io.2
3.0.3-root.io.23.0.7-root.io.13.0.7-root.io.23.0.7-root.io.3
node-handlebars
Ubuntu:18.04:LTS
All versions, plus listed versions
3:4.0.10-5
None known

Public exploits

Links only. Every CVE stores no exploit code.

Public exploits
SourceLinkDate
PoC in GitHubfazilbaig1/CVE-2019-199192024-10-19

History

History
RecordedChangedSources
affected
facts
affected
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV, PoC in GitHub

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2019-19919 is a critical vulnerability (CVSS 9.8) in Handlebars.js Project Handlebars.js, published June 5, 2019. Public exploit code exists. EPSS puts the chance of exploitation in the next 30 days at 7.07%, the 94th percentile. Fixed in handlebars 3.0.8.

References

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