CVE-2026-23550 Modular DS WordPress Plugin Authentication Bypass

Jan 16

BLUF

An actively exploited critical flaw in the Modular DS WordPress plugin allows unauthenticated attackers to take over administrator accounts. Over 40,000 installations are currently at risk.

Executive Cost Summary

This cost analysis was developed by the CyberDax team using expert judgment and assisted analytical tools to support clarity and consistency.

For organizations affected by unauthorized administrator takeover through exploitation of the Modular DS WordPress plugin authentication bypass (CVE-2026-23550):

· Low-end total cost: $75,000 – $180,000

· (single site affected, rapid detection, limited post-exploitation activity)

· Typical expected range: $250,000 – $750,000

· (admin compromise with persistence, multi-day response, external support required)

· Upper-bound realistic scenarios: $1.2M – $3.5M

· (multiple sites managed via plugin, data exposure, regulatory involvement)

Key Cost Drivers

Number of WordPress sites managed through the compromised plugin instance

Time-to-detection allowing attacker persistence or secondary actions

Need for external incident response, forensics, and legal counsel

Presence of customer data, credentials, or transactional systems on affected sites

Business reliance on web presence for revenue or customer operations

Targeted Sectors

· Small to medium businesses

· Organizations using WordPress

Countries

· Global

Date of First Reported Activity

· January 13, 2026

Date of Last Activity Update

· January 16, 2026

CVE-2026-23550

CVSS 3.1

· (10.0) AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Nessus ID

· There is not currently a tenable ID for CVE-2026-23550

Is this currently on the KEV list?

· No

What is the CISA patch by date?

· Not applicable at this time.

APT Names

· CVE-2026-23550 has not been associated with an APT group at this time.

Criminal organization names

· CVE-2026-23550 has not been associated with any criminal organizations at this time.

IOCs

Network & Request Indicators

· Targeted API Endpoint

o Attackers target REST API routes under the prefix /api/modular-connector/.

· Malicious Payloads

o Requests typically attempt to bypass authentication middleware to access administrative functions, such as creating new administrator accounts or modifying site settings.

· Unusual REST API Traffic

o Monitor web server logs for a surge in unauthenticated POST or GET requests to the /wp-json/modular-connector/v1/ namespace from unknown IP addresses.

Host-Based Indicators

· Unauthorized Admin Accounts

o Check for the sudden appearance of new administrator-level users that were not created by authorized personnel.

· Plugin Version

o Any site running Modular DS version 2.5.1 or lower is considered compromised or highly vulnerable.

· Unauthorized File Changes

o Look for modified plugin files or the presence of webshells within the /wp-content/plugins/modular-connector/ directory, which may be deposited after an attacker gains administrative access.

Tools Used

· Automated web scanners and brute-force takeover scripts.

Malware Names

· Not applicable at this time

Malware Sample

Not applicable at this time

TTPs

· T1078.004 Valid Accounts

o Cloud Accounts: Attackers leverage the vulnerability to bypass authentication and gain access to existing administrator accounts without providing valid credentials.

· T1068 Exploitation for Privilege Escalation

o The core of the vulnerability is an "Incorrect Privilege Assignment" flaw that allows unauthenticated remote attackers to elevate their status to that of an administrator.

· T1190 Exploit Public-Facing Application

o Adversaries target the publicly accessible REST-style API routes (specifically under the /api/modular-connector/ prefix) to initiate the attack.

· T1133 External Remote Services

o Since the plugin is used for remote management of multiple sites, exploiting it allows attackers to use the plugin's own intended functionality for remote access.

· T1136.001 Create Account

o Local Account: In observed attacks, once admin access is achieved, attackers frequently create new persistent administrator accounts (often using the username "PoC Admin") to maintain access.

Suggested Rules / potential hunts

As a reminder, these are indicator rules. They are likely to be noisy.

For best results consider creating a data model and reviewing the traffic as a report.

Suricata

Detection focuses on requests to the vulnerable API path with specific bypass parameters (origin=mo).

alert http $EXTERNAL_NET any -> $HTTP_SERVERS any (msg:"ET EXPLOIT Modular DS WordPress Plugin Auth Bypass (CVE-2026-23550)"; flow:established,to_server; content:"/api/modular-connector/"; http_uri; content:"origin=mo"; http_uri; pcre:"/type=[^&]+/U"; reference:cve,2026-23550; classtype:web-application-attack; sid:1000001; rev:1;)

SentinelOne

Search for suspicious admin user creation after exploit

(EventType = "Process Creation" AND ProcessName = "php" AND (CommandLine CONTAINS "wp-admin" OR CommandLine CONTAINS "user-create"))

OR (EventType = "File Modification" AND FilePath CONTAINS "wp-content/plugins/modular-ds")

Splunk

Analysis of web access logs to identify exploitation attempts and unauthorized admin logins.

index=web_logs (uri_path="*/api/modular-connector/*" AND uri_query="*origin=mo*")

| stats count, values(src_ip) as attacker_ips, values(user_agent) as agents by dest, uri_path

| where count > 0

Cross-reference successful hits with WordPress audit logs for new user creation.

splunk

index=wordpress_logs action="user_created" (user="*admin*" OR user_email="*bogus*")

| table _time, src_ip, user, user_email

Delivery Method

· This is a network-based attack

Email samples

Not applicable

References

NVD

· hxxps://nvd.nist.gov/vuln/detail/CVE-2026-23550

Help Modulars

· hxxps://help.modulards.com/en/article/modular-ds-security-release-modular-connector-252-dm3mv0/

CyberDax