XXE in Fusionauth Saml V2
CVE-2021-27736
FusionAuth fusionauth-samlv2 before 0.5.4 allows XXE attacks via a forged AuthnRequest or LogoutRequest because parseFromBytes uses javax.xml.parsers.DocumentBuilderFactory unsafely.
Vulnerability class: XXE (XML External Entity)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N.
EPSS exploit prediction
EPSS: 0.013 (69.5th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 70th percentile — 69.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.013 · newest: 0.013 · change: +0.000
Affected products
Weakness classification (CWE)
Public proof-of-concept exploits
References
- github.com/FusionAuth/fusionauth-samlv2/compare/0.5.3...0.5.4 (Patch, Third Party Advisory)
- github.com/FusionAuth/fusionauth-samlv2/commit/c66fb689d50010662f705d5b585c6388… (Patch, Third Party Advisory)
- www.compass-security.com/fileadmin/Research/Advisories/2021-03_CSNC-2021-004_Fu… (Exploit, Third Party Advisory)
Frequently asked questions
- What is CVE-2021-27736?
- CVE-2021-27736 is a medium-severity vulnerability in Fusionauth Saml V2, classified under Improper Restriction of XML External Entity Reference (XXE). CVSS score: 6.5/10. Published 2021-04-22.
- How severe is CVE-2021-27736?
- Medium severity. CVSS v3 base score is 6.5 out of 10.
- Is CVE-2021-27736 known to be exploited?
- 2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.