CVE-2021-21353Public exploitNetwork attack vector

Remote code execution via unsanitized pretty option

Published Mar 3, 2021 · Updated Apr 16, 2025

Code injection in Pug before 3.0.1 allows remote attackers to execute arbitrary code on a Node.js backend through the pretty option. In pug-code-gen, visitMixin and visitMixinBlock interpolate the pretty string into generated JavaScript without quoting or sanitization. Exploitation requires a server-rendering application to pass attacker-controlled data as the compiler's pretty option, after which injected JavaScript runs with the Node.js process's privileges.

CVSS severity9.0
Critical
EPSS probability4.30%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Code injection in Pug before 3.0.1 allows remote attackers to execute arbitrary code on a Node.js backend through the pretty option. In pug-code-gen, visitMixin and visitMixinBlock interpolate the pretty string into generated JavaScript without quoting or sanitization. Exploitation requires a server-rendering application to pass attacker-controlled data as the compiler's pretty option, after which injected JavaScript runs with the Node.js process's privileges.

The record

CVE
CVE-2021-21353
Published
Mar 3, 2021
Updated
Apr 16, 2025
Vendor
PugJS
Product
Pug
Classifications
T1190, T1059.007
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 3, 2021CVE publishedPublication date reported by the CVE source.
  2. Apr 16, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 3.0.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

PugJS · Pugversion=< 3.0.1

Published CVSS scores

6.8NIST NVDAV:N/AC:M/Au:N/C:P/I:P/A:P
9.0NIST NVDCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

T1190Exploit Public-Facing Application
T1059.007JavaScript/JScript

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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