WordPress Core <= 7.1 - HTML API set_modifiable_text() Comment Boundary Break

2026-09-17 00:00

Strategic Overview

Status: Patched in 6.7.8
Affected Core: WordPress 7.1
Affected Version: 6.7 – 7.1 · 5 branches
CVSS: 3.7Low
Weakness type: CWE-116 · Improper Encoding or Escaping of Output
CVE: CVE pending

At a glance

This record tracks a low-severity Improper Encoding or Escaping of Output vulnerability in the WordPress 7.1 WordPress release line, affecting 6.7 – 7.1 · 5 branches. It carries a CVSS score of 3.7 (reachable over the network). Exploitation requires no authentication. The issue is fixed in version 6.7.8; sites on affected versions should update now. Disclosed September 2026, reported by Jeremy Felt.

Vulnerability Overview

WordPress Core's HTML API WP_HTML_Tag_Processor::set_modifiable_text() (since 6.7.0) used an incomplete comment-closer guard (/--!?>/) that missed the '-?>' abrupt-closing form, allowing text set into an HTML comment node to terminate the comment early. This is developer-facing hardening; there is no first-party sink that turns it into a direct vulnerability. Impact is realized only in plugin/theme code that round-trips attacker-controlled text through the HTML API into a comment node.

Technical Analysis

The vector marks this flaw as remotely reachable over the network, and no privileges on the target site, and no interaction from a victim user.

CWE-116: Improper Encoding or Escaping of Output

The product prepares a structured message for communication with another component, but encoding or escaping of the data is either missing or done incorrectly. As a result, the intended structure of the message is not preserved.

Remediation

Update to one of the following versions, or a newer patched version: 6.7.8, 6.8.9, 6.9.8, 7.0.5, 7.1.1

How does WordSec protect against this?

The fix is the thing that ends this: updating to 6.7.8 is the step that ends it.

Alerts

External References

https://www.wordfence.com/threat-intel/vulnerabilities/id/c41aadb1-e1a6-4bda-ac94-c461c320e78f

Related records

Other vulnerabilities in WordPress 7.1

CVSS Vector

3.7

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

Base

Attack VectorNetwork
Attack ComplexityHigh
Privileges RequiredNone
User InteractionNone
ScopeUnchanged
ConfidentialityNone
IntegrityLow
AvailabilityNone

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