CVE-2026-5090Public exploitNetwork attack vector

Cross-site scripting via unescaped single quotes

Published May 19, 2026 · Updated May 19, 2026

Cross-site scripting in Template::Plugin::HTML 3.102 and earlier allows remote attackers to inject HTML and JavaScript into rendered pages. The html_filter function and HTML.escape method leave single quotes unescaped, letting attacker-controlled values break out of single-quoted attributes and add event handlers. Exploitation requires an application to place untrusted filtered output in a single-quoted attribute and a user to load the resulting page; other reserved characters remain escaped, limiting arbitrary markup injection.

CVSS severity6.1
Medium
EPSS probability0.28%
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 Template::Plugin::HTML 3.102 and earlier allows remote attackers to inject HTML and JavaScript into rendered pages. The html_filter function and HTML.escape method leave single quotes unescaped, letting attacker-controlled values break out of single-quoted attributes and add event handlers. Exploitation requires an application to place untrusted filtered output in a single-quoted attribute and a user to load the resulting page; other reserved characters remain escaped, limiting arbitrary markup injection.

The record

CVE
CVE-2026-5090
Published
May 19, 2026
Updated
May 19, 2026
Vendor
Todd Rinaldo
Product
Template::Plugin::HTML
Classifications
CWE-79, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 19, 2026CVE publishedPublication date reported by the CVE source.
  2. May 19, 2026Record 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 <=3.102

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Todd Rinaldo · Template::Plugin::HTMLversion=0 <=3.102

Published CVSS scores

6.1CISA-ADPCVSS: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.

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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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