# CVE-2026-104803: Auth bypass in WPCOM Member

> Unauthenticated attackers can bypass authentication and log in as any user, including administrators, if social login is configured and identifiers are known.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 10 Oct 2026
- **Updated:** 11 Oct 2026
- **Also known as:** GHSA-gj32-ffvm-frj6

## What is CVE-2026-104803?

CVE-2026-104803 is a critical authentication bypass vulnerability in whyun WPCOM Member, published on 10 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2026-104803?


## How do I fix CVE-2026-104803?

No fix has been published for CVE-2026-104803 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-104803 being exploited?

There is no known exploitation of CVE-2026-104803 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-104803 and fix it if it is affected.

What it is: CVE-2026-104803 is a critical authentication bypass vulnerability in whyun WPCOM Member, published on 10 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-104803 in the wild and no public exploit code.

Affected product: whyun WPCOM Member. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-104803/ (Markdown: https://insights.sbomify.com/CVE-2026-104803/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-104803
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-104803
- OSV: https://osv.dev/vulnerability/CVE-2026-104803

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-104803/
Summaries are generated and may contain mistakes; the official description above is the record.