CVE-2021-24876Public exploitNetwork attack vector

Reflected XSS via unescaped admin-page attribute

Published Nov 29, 2021 · Updated Aug 3, 2024

Reflected XSS in Roundup WP Registrations for the Events Calendar before 2.7.5 allows remote attackers to execute script via a crafted URL. The Registrations admin page inserts the v query parameter into an HTML attribute without output escaping, so an injected attribute event handler executes in the page origin. Exploitation requires a user with access to that WordPress admin page to follow the crafted link, exposing data and actions available in that user's session.

CVSS severity6.1
Medium
EPSS probability1.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Reflected XSS in Roundup WP Registrations for the Events Calendar before 2.7.5 allows remote attackers to execute script via a crafted URL. The Registrations admin page inserts the v query parameter into an HTML attribute without output escaping, so an injected attribute event handler executes in the page origin. Exploitation requires a user with access to that WordPress admin page to follow the crafted link, exposing data and actions available in that user's session.

The record

CVE
CVE-2021-24876
Published
Nov 29, 2021
Updated
Aug 3, 2024
Vendor
Roundup WP
Product
Registrations for the Events Calendar
Classifications
CWE-79, T1204.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 29, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=2.7.5 <2.7.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Roundup WP · Registrations for the Events Calendarversion=2.7.5 <2.7.5

Published CVSS scores

4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:P/A:N
6.1NIST NVDCVSS: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 exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1204.001Malicious Link

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo