# CVE-2026-90977: Clean Login < 1.19 - Unauthenticated CAPTCHA Bypass via Empty Session Comparison

> Unauthenticated attackers can bypass CAPTCHA verification on the registration form to create accounts without solving it.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 18 Sep 2026
- **Updated:** 18 Sep 2026
- **Also known as:** GHSA-whxq-7ph8-rv4q

## What is CVE-2026-90977?

CVE-2026-90977 is a medium-severity vulnerability in Unknown Clean Login, published on 18 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The Clean Login WordPress plugin before 1.19 does not verify its registration CAPTCHA when the stored session value is empty, allowing unauthenticated users to bypass the anti-automation control on the registration form and create accounts without solving it.

Weakness: CWE-697 (Incorrect Comparison)

## Which versions are affected by CVE-2026-90977?


## How do I fix CVE-2026-90977?

No fix has been published for CVE-2026-90977 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-90977 being exploited?

There is no known exploitation of CVE-2026-90977 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90977 and fix it if it is affected.

What it is: CVE-2026-90977 is a medium-severity vulnerability in Unknown Clean Login, published on 18 Sep 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-2026-90977 in the wild and no public exploit code.

Affected product: Unknown Clean Login. 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-2026-90977/ (Markdown: https://insights.sbomify.com/CVE-2026-90977/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90977
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90977
- OSV: https://osv.dev/vulnerability/CVE-2026-90977

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90977/
Summaries are generated and may contain mistakes; the official description above is the record.