CVE-2021-24787

Client Invoicing by Sprout Invoices <= 19.9.6 - Authenticated Stored Cross-Site Scripting

2021-10-18 00:00
Dipak Panchal (th3.d1p4k)

Strategic Overview

Status
Patched in 19.9.7
Affected Plugin
Sprout Invoices – Client Invoicing & Estimates
Affected Version
< 19.9.7
CVSS
4.8Medium
Weakness type
CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CVE
CVE-2021-24787
View all Sprout Invoices – Client Invoicing & Estimates vulnerabilities

At a glance

CVE-2021-24787 is a medium-severity Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in the Sprout Invoices WordPress plugin, affecting versions < 19.9.7. It carries a CVSS score of 4.8 (reachable over the network; low attack complexity). Exploitation requires an authenticated account. The issue is fixed in version 19.9.7; sites on affected versions should update now. Disclosed October 2021, reported by Dipak Panchal (th3.d1p4k).

Vulnerability Overview

The Client Invoicing by Sprout Invoices plugin for WordPress is vulnerable to Stored Cross-Site Scripting in versions up to, and including, 5.5 due to the plugin not sanitising and escaping some of its settings. This makes it possible for high privilege users to inject arbitrary web scripts in pages to perform 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.

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

Reaching this weakness in Sprout Invoices < 19.9.7 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 Sprout Invoices the fix is 19.9.7: builds < 19.9.7 are affected, anything from 19.9.7 onward is not.

Remediation

Update to version 19.9.7, or a newer patched version

How does WordSec protect against this?

The attempt arrives as an ordinary request to Sprout Invoices: WordSec's web application firewall inspects request payloads before WordPress loads them. None of that substitutes for the fix: Sprout Invoices 19.9.7 closes this, and updating the plugin is the step that ends it.

  • Firewall
  • Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2021-24787https://www.wordfence.com/threat-intel/vulnerabilities/id/59cdb3e3-06ca-4325-9dae-73ad3cdfd910https://nvd.nist.gov/vuln/detail/CVE-2021-24787

Related records

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