# CVE-2026-72584: fastschema - TOCTOU Race Condition Bypasses OTP Attempt Limit in Account Recovery

> An attacker can bypass OTP attempt limits via a race condition to brute-force account recovery codes, potentially taking over user accounts.

- **Severity:** High 7.4 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/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-qm6j-5qpg-x2x4

## What is CVE-2026-72584?

CVE-2026-72584 is a high-severity vulnerability in fastschema, 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 time-of-check/time-of-use (TOCTOU) race condition in fastschema through v0.15.1 allows an unauthenticated remote attacker to bypass the OTP attempt limit on the account recovery flow, enabling brute-force attacks on 6-digit OTP codes.

Weakness: CWE-367 (Time-of-check Time-of-use (TOCTOU) Race Condition)

## Which versions are affected by CVE-2026-72584?


## How do I fix CVE-2026-72584?

No fix has been published for CVE-2026-72584 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-72584 being exploited?

There is no known exploitation of CVE-2026-72584 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-72584 and fix it if it is affected.

What it is: CVE-2026-72584 is a high-severity vulnerability in fastschema, 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-2026-72584 in the wild and no public exploit code.

Affected product: fastschema. 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-2026-72584/ (Markdown: https://insights.sbomify.com/CVE-2026-72584/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-72584
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-72584
- OSV: https://osv.dev/vulnerability/CVE-2026-72584

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-72584/
Summaries are generated and may contain mistakes; the official description above is the record.