# CVE-2026-72588: bluewave-labs Checkmate - User Enumeration via Differential HTTP Response in Password Recovery

> Unauthenticated attackers can enumerate valid user accounts by observing differential HTTP responses in the password recovery endpoint.

- **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:** 10 Aug 2026
- **Updated:** 10 Aug 2026
- **Also known as:** GHSA-cjr5-m69m-f39c

## What is CVE-2026-72588?

CVE-2026-72588 is a medium-severity vulnerability in bluewave-labs Checkmate, published on 10 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A user enumeration vulnerability in bluewave-labs/Checkmate through 2.1.0 allows an unauthenticated remote attacker to determine whether a given email address is registered. The POST /api/v1/auth/recovery/request endpoint returns HTTP 200 for registered email addresses and a different status code for unregistered ones, enabling attackers to enumerate valid user accounts.

Weakness: CWE-204 (Observable Response Discrepancy)

## Which versions are affected by CVE-2026-72588?


## How do I fix CVE-2026-72588?

No fix has been published for CVE-2026-72588 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-72588 being exploited?

There is no known exploitation of CVE-2026-72588 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-72588 and fix it if it is affected.

What it is: CVE-2026-72588 is a medium-severity vulnerability in bluewave-labs Checkmate, published on 10 Aug 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-2026-72588 in the wild and no public exploit code.

Affected product: bluewave-labs Checkmate. 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-2026-72588/ (Markdown: https://insights.sbomify.com/CVE-2026-72588/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-72588
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-72588
- OSV: https://osv.dev/vulnerability/CVE-2026-72588

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-72588/
Summaries are generated and may contain mistakes; the official description above is the record.