CVE-2021-27736

MEDIUM 6.5CVE-2021-27736 · Published 22/04/2021 · updated 17/06/2026

In short

CVE-2021-27736 is a MEDIUM (CVSS 6.5) vulnerability affecting saml v2 (fusionauth).
Chance of exploitation in the next 30 days (EPSS): 1.3%, higher than 70.8% of all vulnerabilities.
Fix: update to 0.5.4 or later.

Package	Affected versions	Patched versions
saml v2 fusionauth	`< 0.5.4`	`0.5.4`

Description

FusionAuth fusionauth-samlv2 before 0.5.4 allows XXE attacks via a forged AuthnRequest or LogoutRequest because parseFromBytes uses javax.xml.parsers.DocumentBuilderFactory unsafely.

References

FusionAuth/fusionauth-samlv2 commit c66fb68 · Patch
FusionAuth/fusionauth-samlv2 · Patch
compass-security.com/fileadmin/Research/Advisories/2021-03_CSNC-2021-004_FusionAuth_SAML_Library_XML_External_Entity.txt · Exploit

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