# CVE-2026-39923: Flarum < 1.8.16 Password Reset Token Expiry Bypass via POST /reset

> Unauthenticated attackers can reuse expired password reset tokens to change any user's password and gain account access.

- **Severity:** Critical 9.2 (`CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 5 Aug 2026
- **Updated:** 14 Aug 2026
- **Also known as:** GHSA-3mr9-883x-4f3x

## What is CVE-2026-39923?

CVE-2026-39923 is a critical authentication bypass vulnerability in Flarum Framework, published on 5 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Flarum before 1.8.16 contains a password reset token expiry bypass vulnerability that allows unauthenticated attackers to reuse expired password reset tokens by submitting them directly to the reset processing endpoint. The SavePasswordController::handle() method calls PasswordToken::findOrFail() without performing any expiry validation, allowing attackers to bypass the 24-hour token lifetime enforced only during form rendering and change any account's password to gain an authenticated session.

Weakness: CWE-324 (Use of a Key Past its Expiration Date)

## Which versions are affected by CVE-2026-39923?


## How do I fix CVE-2026-39923?

No fix has been published for CVE-2026-39923 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-39923 being exploited?

There is no known exploitation of CVE-2026-39923 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-39923 and fix it if it is affected.

What it is: CVE-2026-39923 is a critical authentication bypass vulnerability in Flarum Framework, published on 5 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-2026-39923 in the wild and no public exploit code.

Affected product: Flarum Framework. 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-2026-39923/ (Markdown: https://insights.sbomify.com/CVE-2026-39923/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-39923
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-39923
- OSV: https://osv.dev/vulnerability/CVE-2026-39923

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-39923/
Summaries are generated and may contain mistakes; the official description above is the record.