CVE-2020-13959Network attack vector

Browser script execution via unescaped template path

Published Mar 10, 2021 · Updated Feb 13, 2025

Reflected XSS in Apache Velocity Tools before 3.1 allows remote attackers to execute JavaScript through a crafted VelocityView URL. VelocityViewServlet.error appends the requested template path directly to its generated HTML error page without escaping it. Exploitation requires a user to follow a crafted URL for a nonexistent template, exposing that user's session to script-driven data theft or actions.

CVSS severity6.1
Medium
EPSS probability5.72%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reflected XSS in Apache Velocity Tools before 3.1 allows remote attackers to execute JavaScript through a crafted VelocityView URL. VelocityViewServlet.error appends the requested template path directly to its generated HTML error page without escaping it. Exploitation requires a user to follow a crafted URL for a nonexistent template, exposing that user's session to script-driven data theft or actions.

The record

CVE
CVE-2020-13959
Published
Mar 10, 2021
Updated
Feb 13, 2025
Vendor
The Apache Software Foundation
Product
Apache Velocity Tools
Classifications
CWE-79, T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 10, 2021CVE publishedPublication date reported by the CVE source.
  2. Feb 13, 2025Record 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=Apache Velocity Tools <3.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Apache Software Foundation · Apache Velocity Toolsversion=Apache Velocity Tools <3.1

Published CVSS scores

6.1GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/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 exploitUnconfirmed

Weakness, pattern, technique

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

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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