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CVE-2026-109515 critical CVSS 9.8

Privilege Escalation in WordPress (CVE-2026-109515)

Summary

Vulnerability in WordPress (CVE-2026-109515). Successful exploitation can lead to full system takeover. Exploitable via subscribe_to_email_list.

Original description

The description as published by the source.

The MailOptin – Popup, Optin Forms & Email Newsletters for Mailchimp, HubSpot, AWeber Etc. plugin for WordPress is vulnerable to Privilege Escalation in all versions up to, and including, 1.2.78.6 This is due to the subscribe_to_email_list endpoint accepting an attacker-supplied optin_data[form_custom_field_mappings] parameter without any allow-list validation on destination keys, allowing the attacker-controlled mapping to override the administrator's saved mapping and pass arbitrary wp_users column names — including ID and user_pass — directly into wp_insert_user() via the subscribe() function. This makes it possible for unauthenticated attackers to force wp_insert_user() into UPDATE mode on any existing account by supplying a target user's numeric ID, overwrite that account's password with a pre-hashed value of their choosing, and thereby take over any WordPress user account — including administrators — leading to full site compromise. Exploitation requires that a WordPress User Registration opt-in form is published somewhere on the site, though the form's UUID is visible in page source and no authentication, nonce, or capability check is required to reach the vulnerable endpoint.

Source: GitHub Security Advisories (Global) NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-109515 has been found in WordPress.
Attackers can target a specific entry point like subscribe_to_email_list over the network to misuse the product.
Successful exploitation can lead to full system takeover. CVSS score: 9.8/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "WordPress CVE-2026-109515" on the vendor's site.

CVE-2026-109515 (WordPress) — CWE-269 / CVSS v3 9.8
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: subscribe_to_email_list / wp_users / user_pass
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

A vulnerability (CWE-269) exists in WordPress. Attackers reach the vulnerable code path via subscribe_to_email_list without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of WordPress. Attack surface: subscribe_to_email_list / wp_users / user_pass.

🔥 Severity

Severity: Critical (CVSS 9.8/10). Successful exploitation can lead to full system takeover.

🔧 How to fix

Update to the patched release per vendor advisory.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    Audit SBOM/dependencies for affected components.

    資産台帳・SBOM・依存マニフェストで WordPress を使っているサービスとバージョンを洗い出す。

  2. 2
    Post-deployment verification verify 
    Confirm patched version is live in production

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

References

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