CVE-2021-23342Public exploitNetwork attack vector

DOM XSS via malformed remote sidebar URLs

Published Feb 19, 2021 · Updated Sep 16, 2024

DOM-based XSS in Docsify before 4.12.1 allows remote attackers to execute JavaScript by directing a user to a crafted documentation URL. The route parser's isExternal regular expression treats URLs with more than two leading slashes as local, and remote sidebar HTML reaches rendering without the main-page sanitization. Exploitation requires user interaction with the crafted URL; injected script executes in the documentation site's browser context and can read or modify accessible page data.

CVSS severity6.1
Medium
EPSS probability1.66%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

DOM-based XSS in Docsify before 4.12.1 allows remote attackers to execute JavaScript by directing a user to a crafted documentation URL. The route parser's isExternal regular expression treats URLs with more than two leading slashes as local, and remote sidebar HTML reaches rendering without the main-page sanitization. Exploitation requires user interaction with the crafted URL; injected script executes in the documentation site's browser context and can read or modify accessible page data.

The record

CVE
CVE-2021-23342
Published
Feb 19, 2021
Updated
Sep 16, 2024
Vendor
docsifyjs
Product
Docsify
Classifications
CWE-79, T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 19, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 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=unspecified <4.12.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

docsifyjs · Docsifyversion=unspecified <4.12.0

Published CVSS scores

6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/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.

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

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1189Drive-by Compromise

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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