CVE-2021-24943

Registrations for the Events Calendar <= 2.7.5 - Unauthenticated SQL Injection

2021-11-08 00:00
Krzysztof Zając

Strategic Overview

Status
Patched in 2.7.6
Affected Plugin
Registrations for the Events Calendar – Event Registration Plugin
Affected Version
< 2.7.6
CVSS
9.8Critical
Weakness type
CWE-89 · Improper Neutralization of Special Elements used in an SQL Command ('SQL Injection')
CVE
CVE-2021-24943
View all Registrations for the Events Calendar – Event Registration Plugin vulnerabilities

At a glance

CVE-2021-24943 is a critical-severity Improper Neutralization of Special Elements used in an SQL Command ('SQL Injection') vulnerability in the Registrations for the Events Calendar WordPress plugin, affecting versions < 2.7.6. It carries a CVSS score of 9.8 (reachable over the network; low attack complexity; high confidentiality, integrity, availability impact). Exploitation requires no authentication. The issue is fixed in version 2.7.6; sites on affected versions should update now. Disclosed November 2021, reported by Krzysztof Zając.

Vulnerability Overview

The Registrations for the Events Calendar WordPress plugin before 2.7.6 does not sanitise and escape the event_id in the rtec_send_unregister_link AJAX action (available to both unauthenticated and authenticated users) before using it in a SQL statement, leading to an unauthenticated SQL injection.

Technical Analysis

The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed, and no privileges on the target site, and no interaction from a victim user. A successful exploit has high impact on confidentiality, integrity, availability — full site compromise territory.

CWE-89: Improper Neutralization of Special Elements used in an SQL Command ('SQL Injection')

Reaching this weakness in Registrations for the Events Calendar < 2.7.6 takes no account at all. SQL injection happens when request data is concatenated into a query instead of being bound as a parameter, letting an attacker change the structure of the statement rather than just its values.

A working injection can read any table the database user can see, which on a WordPress install means user records, password hashes and session or API secrets stored in options. For Registrations for the Events Calendar the fix is 2.7.6: builds < 2.7.6 are affected, anything from 2.7.6 onward is not.

Remediation

Update to version 2.7.6, or a newer patched version

How does WordSec protect against this?

Requests carrying this pattern arrive without a session, so nothing upstream of the firewall gets a chance to reject them: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: Registrations for the Events Calendar 2.7.6 closes this, and updating the plugin is the step that ends it.

  • Firewall
  • Login Security
  • Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2021-24943https://www.wordfence.com/threat-intel/vulnerabilities/id/b8c18081-1ee3-4072-89f1-b6eb1518916ehttps://nvd.nist.gov/vuln/detail/CVE-2021-24943

Related records

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