# CVE-2026-48611: Auth bypass in phpBB

> Attackers can hijack accounts in default phpBB installations due to improper OAuth authentication checks, leading to unauthorized access.

- **Severity:** Critical 9.8 (`CVSS:3.0/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:** 12 Jun 2026
- **Updated:** 12 Jun 2026
- **Also known as:** GHSA-24pr-8ggp-h88c

## What is CVE-2026-48611?

CVE-2026-48611 is a critical authentication bypass vulnerability in phpBB, published on 12 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Improper authentication checks in the OAuth implementation allow account hijacking even when OAuth is not configured or enabled leading to unauthorized access in default installations.

Weakness: CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2026-48611?


## How do I fix CVE-2026-48611?

No fix has been published for CVE-2026-48611 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-48611 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-48611 exists.

Public exploit code:

- Bypass Authentication (github_poc): https://github.com/lxdwnpiper/CVE-2026-48611-phpBB
- Automated PoC for CVE-2026-48611 — phpBB OAuth login_link authentication bypass (github_poc): https://github.com/Ethicalgrey/phpBB-CVE-2026-48611
- phpBB < 3.3.17 - Authentication Bypass (nuclei): http/cves/2026/CVE-2026-48611.yaml

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-48611 and fix it if it is affected.

What it is: CVE-2026-48611 is a critical authentication bypass vulnerability in phpBB, published on 12 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-48611 exists.

Affected product: phpBB. 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-2026-48611/ (Markdown: https://insights.sbomify.com/CVE-2026-48611/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-48611
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-48611
- OSV: https://osv.dev/vulnerability/CVE-2026-48611

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-48611/
Summaries are generated and may contain mistakes; the official description above is the record.