CVE-2021-27736 json
FusionAuth fusionauth-samlv2 before 0.5.4 allows XXE attacks via a forged AuthnRequest or LogoutRequest because parseFromBytes uses javax.x…
published 2021-04-22 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-14478
- cvss
- 6.5
- version 3.1, NVD
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 1.3%
- EPSS 1.3% chance of exploitation in 30 days, percentile 70%
- public exploits
- 0
- none known
Summary
FusionAuth fusionauth-samlv2 before 0.5.4 allows XXE attacks via a forged AuthnRequest or LogoutRequest because parseFromBytes uses javax.xml.parsers.DocumentBuilderFactory unsafely.
Patch / fix
- fusionauth saml_v2 0.5.4
Exploit prediction
1.32% chance of exploitation in the next 30 days, higher than 70% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- compass-security.com https://www.compass-security.com/fileadmin/Research/Advisories/2021-03_CSNC-2021-004_FusionAuth_SAML_Library_XML_External_Entity.txt referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| NVD | 3.1 | 6.5 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N |
| NVD | 2.0 | 4.0 | AV:N/AC:L/Au:S/C:P/I:N/A:N |
Classification
- Weakness
-
- CWE-611 Improper Restriction of XML External Entity Reference
References
-
github.com
/FusionAuth/fusionauth-samlv2/commit/c66fb689d50010662f705d5b585c6388ce555dbd
patch, third-party-advisory
-
github.com
/FusionAuth/fusionauth-samlv2/compare/0.5.3...0.5.4
patch, third-party-advisory
-
compass-security.com
/fileadmin/Research/Advisories/2021-03_CSNC-2021-004_FusionAuth_SAML_Library_XML_External_Entity.txt
exploit, third-party-advisory
Sources
- CVE List CVE-2021-27736
- NVD CVE-2021-27736
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