WordPress security changelog
CRITICAL CVE-2026-104803 Received

WPCOM Member: Privilege escalation or authentication bypass

An unauthenticated attacker can abuse the social-login callback init handler’s uuid/code flow. Missing nonce/OAuth-state binding and globally shared storage allow attacker-written login data to be consumed by weapp_new_user, which resolves a forged openid and calls wp_set_auth_cookie. Exploitation requires a configured social provider and a known or discoverable victim openid/unionid. It can impersonate that account, including an administrator when those prerequisites hold; the export does not name a complete callback URL. Affected versions: <= 1.7.27. No fixed release is confirmed. Upstream 1.8.0.1 is available and may resolve the issue, but the official changelog does not clearly establish that it fixes this CVE.

CVE / CNA score 9.8 CVSS 3.1 · security@wordfence.com
NVD score Pending NVD has not published its own CVSS assessment.
Component
WPCOM Member
Plugin slug
wpcom-member
Affected
<= 1.7.27
Safe version
See mitigation notes
Published
Oct 10, 2026
Weakness
CWE-287 — Improper Authentication

This CVE was published Oct 10, 2026 and is one of 8 known issues for this plugin.

What to do

Update, patch or deactivate.

No fixed release is confirmed. Upstream 1.8.0.1 is available and may resolve the issue, but the official changelog does not clearly establish that it fixes this CVE. Disable the affected feature or deactivate the component until a confirmed fix is available. Application-level remediation: Bind OAuth state and callback data to one browser session and provider, verify the provider response, and consume login state once. Never resolve a local account from attacker-writable shared callback data.

No confirmed safe version is listed. Consider a vendor-supported patch or temporarily restricting the affected functionality while you assess the risk.

Deactivate only when warranted by your risk profile, or when advised by your hosting provider in the limited circumstances where the vulnerability cannot otherwise be mitigated. If you’re unsure which action is appropriate, contact Fused or your hosting provider for guidance.

Source record

Technical description

The WPCOM Member plugin for WordPress is vulnerable to Authentication Bypass in all versions up to, and including, 1.7.27 via the `uuid` and `code` parameters of the social-login callback handler registered on the `init` hook. The vulnerability exists because the `login` function's social-login flow performs no nonce validation, no OAuth state verification, and no per-visitor namespace isolation in the session store, allowing an unauthenticated attacker to issue a crafted GET request that writes an attacker-named, attacker-valued entry into the global session namespace (bypassing the per-visitor prefix by prepending an underscore), then issue a second GET request triggering `weapp_new_user()` to read that forged entry and resolve the attacker-supplied `openid` value to a bound WordPress account before `wp_set_auth_cookie()` establishes a fully authenticated session. This makes it possible for unauthenticated attackers to log in as any WordPress user — including administrators — whose bound social provider identifier (openid/unionid) is known or discoverable. Successful exploitation requires that the target site has at least one social provider configured (which activates the vulnerable handler) and that the attacker knows or can enumerate the victim account's bound openid or unionid.

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

References

Primary and upstream sources