CVE-2026-15826

Published

15 August 2026

Modified

20 August 2026

CVSS Score v3.1 9.8

Click a component to see what it means

Raw vector

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

EPSS Score 0.025 83th percentile

Risk Priority 75 floored blend · peak EPSS

Summary

CVE-2026-15826 is a critical-severity Incorrect Type Conversion or Cast (CWE-704) vulnerability in Wordpress (inferred from references). Its CVSS base score is 9.8 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked in the top 17% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SA-15 (Development Process, Standards, and Tools) — see the control section below for these in your framework.

EU & UK References

🇪🇺 ENISA EUVD: EUVD-2026-59593

Vulnerability Data

The User Profile Builder plugin for WordPress is vulnerable to Authentication Bypass via Type Confusion in versions up to, and including, 3.16.4. This is due to the wppb_log_in_user() function calling absint() on the return value of wp_insert_user() before performing an…

is_wp_error() check — when a registration is submitted with a 61–70 character username, WordPress core rejects it with a WP_Error object, but absint() coerces that object to the integer 1 before the error check can short-circuit execution, causing the plugin to bind and return a transient-backed autologin nonce tied to user ID 1. This makes it possible for unauthenticated attackers to log in as the site's Administrator account (user ID 1), resulting in full administrative takeover of the site.

CWE(s): CWE-704

Related Threats

MITRE ATT&CK Enterprise Techniques

T1068 Exploitation for Privilege Escalation Privilege Escalation

Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.

attack.mitre.org →

T1190 Exploit Public-Facing Application Initial Access

Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.

attack.mitre.org →

T1203 Exploitation for Client Execution Execution

Adversaries may exploit software vulnerabilities in client applications to execute code.

attack.mitre.org →

T1210 Exploitation of Remote Services Lateral Movement

Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.

attack.mitre.org →

T1212 Exploitation for Credential Access Credential Access

Adversaries may exploit software vulnerabilities in an attempt to collect credentials.

attack.mitre.org →

T1687 Exploitation for Defense Impairment Defense Impairment

Adversaries may exploit vulnerabilities in security software, infrastructure, or defensive components to degrade, disable, or otherwise continue to impair their ability to prevent, detect, or respond to malicious activity.

attack.mitre.org →

Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-42576Shared CWE-704

CVE-2026-48140Shared CWE-704

CVE-2025-54429Shared CWE-704

CVE-2023-21638Shared CWE-704

CVE-2026-25613Shared CWE-704

CVE-2025-40539Shared CWE-704

CVE-2025-62494Shared CWE-704

CVE-2026-6726Shared CWE-704

CVE-2023-6249Shared CWE-704

CVE-2024-47181Shared CWE-704

Affected Assets

Wordpress

—

inferred from references and description; NVD did not file a CPE for this CVE

Mitigating Controls

Mitigating Controls (NIST 800-53 r5) AI

SA-11 Developer Testing and Evaluation good match

Developer testing and evaluation (static analysis, fuzzing, unit tests) directly finds incorrect type conversions or casts.

SA-15 Development Process, Standards, and Tools partial match

Requiring documented development standards and tools can mandate safe typing, casting rules, and compiler checks that stop the weakness from being introduced.

SA-8 Security and Privacy Engineering Principles partial match

Security engineering principles can require type-safe design and casting practices that structurally avoid incorrect conversions.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match

prevents

Secure SDLC practices directly prevent type-conversion flaws via coding standards, reviews, and testing.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match

finds

Security testing can uncover type-conversion defects before release.

A.8.25 Secure development life cycle partial match

prevents

Secure development lifecycle includes type-safety reviews that reduce incorrect casts.

A.8.26 Application security requirements partial match

prevents

Application security requirements can mandate strong typing and safe casting rules.

A.8.27 Secure system architecture and engineering principles partial match

degrades

Secure architecture principles discourage unsafe type conversions in design.