What is CVE-2021-38555?

CVE-2021-38555 is a critical-severity vulnerability in Apache Any23, classified under Improper Restriction of XML External Entity Reference (XXE). CVSS score: 9.1/10. Published 2021-09-11.

How severe is CVE-2021-38555?

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

XXE in Apache Any23

CVE-2021-38555

An XML external entity (XXE) injection vulnerability was discovered in the Any23 StreamUtils.java file and is known to affect Any23 versions < 2.5. XML external entity injection (also known as XXE) is a web security vulnerability that allows an attacker to interfere with an application's processing of XML data. It often allows an attacker to view files on the application server filesystem, and to interact with any back-end or external systems that the application itself can access.

Vulnerability class: XXE (XML External Entity)

Published 2021-09-11 · 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:H/A:N.

EPSS exploit prediction

EPSS: 0.028 (85.7th percentile), scored 2026-10-02.

Low probability of exploitation in the next 30 days, but still tracked. 86th percentile — 85.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.028 · newest: 0.028 · change: 0.000

Affected products

Apache Any23
Apache Software Foundation Any23 — versions Apache Any23

Weakness classification (CWE)

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

References

lists.apache.org/thread.html/r589d1a9f94dbeee7a0f5dbe8513a0e300dfe669bd964ba2fb… (Mailing List, Vendor Advisory)

Frequently asked questions

What is CVE-2021-38555?: CVE-2021-38555 is a critical-severity vulnerability in Apache Any23, classified under Improper Restriction of XML External Entity Reference (XXE). CVSS score: 9.1/10. Published 2021-09-11.
How severe is CVE-2021-38555?: Critical severity. CVSS v3 base score is 9.1 out of 10.