CVE-2026-14827Public exploitNetwork attack vector

Stored XSS via unescaped event link attribute

Published Jul 27, 2026 · Updated Jul 27, 2026

Stored XSS in event link field of Kieran O'Shea Calendar before 1.3.18 allows remote authenticated users to execute JavaScript in visitors' browsers. The event_link value is stored and then inserted into a public calendar anchor's href attribute without attribute-context escaping, so a quote can add an event handler. Contributor access is sufficient under the default edit_posts setting, and a visitor triggers the script by viewing the calendar and moving the pointer over the crafted link.

CVSS severity6.8
Medium
EPSS probability0.23%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in event link field of Kieran O'Shea Calendar before 1.3.18 allows remote authenticated users to execute JavaScript in visitors' browsers. The event_link value is stored and then inserted into a public calendar anchor's href attribute without attribute-context escaping, so a quote can add an event handler. Contributor access is sufficient under the default edit_posts setting, and a visitor triggers the script by viewing the calendar and moving the pointer over the crafted link.

The record

CVE
CVE-2026-14827
Published
Jul 27, 2026
Updated
Jul 27, 2026
Vendor
Kieran O'Shea
Product
Calendar
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 27, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 27, 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 <1.3.18

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Kieran O'Shea · Calendarversion=0 <1.3.18

Published CVSS scores

6.8CISA ADPCVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/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.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1059.007JavaScript

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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