What is CVE-2021-20399?

CVE-2021-20399 is a critical-severity vulnerability in IBM Qradar Security Information And Event Manager, classified under Improper Restriction of XML External Entity Reference (XXE). CVSS score: 9.1/10. Published 2021-07-27.

How severe is CVE-2021-20399?

Critical severity. CVSS v3 base score is 9.1 out of 10.

XXE in IBM Qradar Security Information And Event Manager

CVE-2021-20399

IBM Qradar SIEM 7.3.0 to 7.3.3 Patch 8 and 7.4.0 to 7.4.3 GA is vulnerable to an XML External Entity Injection (XXE) attack when processing XML data. A remote attacker could exploit this vulnerability to expose sensitive information or consume memory resources. IBM X-Force ID: 196073.

Vulnerability class: XXE (XML External Entity)

Published 2021-07-27 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H.

EPSS exploit prediction

EPSS: 0.018 (78.0th percentile), scored 2026-10-21.

Low probability of exploitation in the next 30 days, but still tracked. 78th percentile — 78.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.018 · newest: 0.018 · change: 0.000

Affected products

IBM Qradar Security Information And Event Manager — versions 7.3.3, 7.4.3
IBM Qradar Siem — versions 7.3.0, 7.4.0, 7.4.3
Linux Kernel

Weakness classification (CWE)

CWE-611 — Improper Restriction of XML External Entity Reference (XXE)

References

www.ibm.com/support/pages/node/6475263 (Patch, Vendor Advisory)
exchange.xforce.ibmcloud.com/vulnerabilities/196073 (VDB Entry, vdb-entry, Vendor Advisory)

Frequently asked questions

What is CVE-2021-20399?: CVE-2021-20399 is a critical-severity vulnerability in IBM Qradar Security Information And Event Manager, classified under Improper Restriction of XML External Entity Reference (XXE). CVSS score: 9.1/10. Published 2021-07-27.
How severe is CVE-2021-20399?: Critical severity. CVSS v3 base score is 9.1 out of 10.