WordPress Core 4.7.0 - 7.1.2 - Authenticated (Contributor+) Denial of Service via Block Editor URL Details

2026-10-07 00:00
Anthropic

Strategic Overview

Status
Patched in 4.7.38
Affected Core
WordPress 7.1
Affected Version
4.7.0 – 7.1.2 · 25 branches
CVSS
4.3Medium
Weakness type
CWE-835 · Loop with Unreachable Exit Condition ('Infinite Loop')
CVE
CVE pending
View all WordPress 7.1 vulnerabilities

At a glance

This record tracks a medium-severity Loop with Unreachable Exit Condition ('Infinite Loop') vulnerability in the WordPress 7.1 WordPress release line, affecting 4.7.0 – 7.1.2 · 25 branches. It carries a CVSS score of 4.3 (reachable over the network; low attack complexity). Exploitation requires an authenticated account at Contributor level or above. The issue is fixed in version 4.7.38; sites on affected versions should update now. Disclosed October 2026, reported by Anthropic.

Vulnerability Overview

WordPress Core is vulnerable to Denial of Service in versions 4.7 through 7.1.2 because WP_Http::make_absolute_url() can enter a non-terminating loop when a malformed relative path contains a parent-directory component that its replacement expression cannot remove. In the demonstrated Core path, this makes it possible for authenticated attackers with Contributor-level access and above to occupy a PHP worker by asking the Block Editor URL Details endpoint to process attacker-controlled remote HTML containing a malformed relative icon or image URL. Repeated concurrent requests may reduce site availability.

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-835: Loop with Unreachable Exit Condition ('Infinite Loop')

The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop.

Remediation

Update to one of the following versions, or a newer patched version: 4.7.38, 4.8.33, 4.9.34, 5.0.30, 5.1.27, 5.2.29, 5.3.26, 5.4.24, 5.5.23, 5.6.22, 5.7.20, 5.8.18, 5.9.19, 6.0.17, 6.1.15, 6.2.14, 6.3.13, 6.4.13, 6.5.13, 6.6.10, 6.7.10, 6.8.11, 6.9.10, 7.0.7, 7.1.3

How does WordSec protect against this?

The fix is the thing that ends this: updating to 4.7.38 is the step that ends it.

  • Alerts

External References

https://www.wordfence.com/threat-intel/vulnerabilities/id/bc5886e8-a520-48e4-9976-2e92b37e4bdf

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