CVE-2021-23416Public exploitNetwork attack vector

Browser script execution via unencoded template substitution

Published Jul 28, 2021 · Updated Sep 17, 2024

Cross-site scripting in magynhard curly-bracket-parser 1.0.2 and earlier allows remote attackers to execute script via template input. The parse method passes variable values to _replaceAll for direct insertion into the output string without context-aware encoding. Exploitation requires an application to render attacker-controlled substitutions as HTML and a user to view the output; injected script then runs in that user's browser.

CVSS severity5.4
Medium
EPSS probability0.79%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site scripting in magynhard curly-bracket-parser 1.0.2 and earlier allows remote attackers to execute script via template input. The parse method passes variable values to _replaceAll for direct insertion into the output string without context-aware encoding. Exploitation requires an application to render attacker-controlled substitutions as HTML and a user to view the output; injected script then runs in that user's browser.

The record

CVE
CVE-2021-23416
Published
Jul 28, 2021
Updated
Sep 17, 2024
Vendor
magynhard
Product
curly-bracket-parser
Classifications
CWE-79, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 28, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 17, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=0 <unspecified

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

magynhard · curly-bracket-parserversion=0 <unspecified

Published CVSS scores

6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
5.4SnykCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:P/A:N

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.

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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

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1203Exploitation for Client Execution

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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