CVE-2021-24686

SVG Support <= 2.3.19 Admin+ Cross-Site Scripting

2022-01-03 00:00

Strategic Overview

Status: Patched in 2.3.20
Affected Plugin: SVG Support
Affected Version: <= 2.3.19
CVSS: 5.5Medium
Weakness type: CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CVE: CVE-2021-24686

At a glance

CVE-2021-24686 is a medium-severity Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in the SVG Support WordPress plugin, affecting versions <= 2.3.19. It carries a CVSS score of 5.5 (reachable over the network; low attack complexity). The issue is fixed in version 2.3.20; sites on affected versions should update now. Disclosed January 2022, reported by Shivam Rai.

Vulnerability Overview

The SVG Support WordPress plugin before 2.3.20 does not escape the "CSS Class to target" setting before outputting it in an attribute, which could allow high privilege users to perform Cross-Site Scripting attacks even when the unfiltered_html capability is disallowed.

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 interaction from a victim user.

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

Reaching this weakness in SVG Support <= 2.3.19 takes a caller who can reach the endpoint. 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 SVG Support the fix is 2.3.20: builds <= 2.3.19 are affected, anything from 2.3.20 onward is not.

Remediation

Update to version 2.3.20, or a newer patched version

How does WordSec protect against this?

The attempt arrives as an ordinary request to SVG Support: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: SVG Support 2.3.20 closes this, and updating the plugin is the step that ends it.

Firewall
Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2021-24686 https://www.wordfence.com/threat-intel/vulnerabilities/id/9e9fcaf5-d531-4b14-b8b1-d8090243cf0c https://nvd.nist.gov/vuln/detail/CVE-2021-24686

Related records

Same weakness class

Other vulnerabilities in SVG Support

CVSS Vector

5.5

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

Base

Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredHigh
User InteractionNone
ScopeChanged
ConfidentialityLow
IntegrityLow
AvailabilityNone

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