CVE-2018-18872

Calendar <= 1.3.10 - Authenticated Stored Cross-Site Scripting

2018-10-30 00:00

Strategic Overview

Status: Patched in 1.3.11
Affected Plugin: Calendar
Affected Version: < 1.3.11
CVSS: 5.4Medium
Weakness type: CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CVE: CVE-2018-18872

At a glance

CVE-2018-18872 is a medium-severity Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in the Calendar WordPress plugin, affecting versions < 1.3.11. It carries a CVSS score of 5.4 (reachable over the network; low attack complexity). Exploitation requires an authenticated account. The issue is fixed in version 1.3.11; sites on affected versions should update now. Disclosed October 2018, reported by boombyte.

Vulnerability Overview

The Kieran O'Shea Calendar plugin before 1.3.11 for WordPress has Stored XSS via the event_title parameter in a wp-admin/admin.php?page=calendar add action, or the category name during category creation at the wp-admin/admin.php?page=calendar-categories URI.

Technical Analysis

The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed.

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

Reaching this weakness in Calendar < 1.3.11 takes any authenticated account. Cross-site scripting happens when input from a request is written into a page without being escaped for the context it lands in, so the browser parses attacker-supplied text as markup or script.

Injected script runs with the privileges of whoever views the affected page, which is how these flaws turn into administrator session theft, silent account creation or persistent backdoors in page content. For Calendar the fix is 1.3.11: builds < 1.3.11 are affected, anything from 1.3.11 onward is not.

Remediation

Update to version 1.3.11, or a newer patched version

How does WordSec protect against this?

The attempt arrives as an ordinary request to Calendar: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: Calendar 1.3.11 closes this, and updating the plugin is the step that ends it.

Firewall
Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2018-18872 https://www.wordfence.com/threat-intel/vulnerabilities/id/e3e2efbf-11ac-4a85-8136-cb40468089e1 https://nvd.nist.gov/vuln/detail/CVE-2018-18872

Related records

Same weakness class

Other vulnerabilities in Calendar

CVSS Vector

5.4

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

Base

Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredLow
User InteractionRequired
ScopeChanged
ConfidentialityLow
IntegrityLow
AvailabilityNone

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