What is CVE-2021-3312?

CVE-2021-3312 is a medium-severity vulnerability in Alkacon Opencms, classified under Improper Restriction of XML External Entity Reference (XXE). CVSS score: 6.5/10. Published 2021-10-08.

How severe is CVE-2021-3312?

Medium severity. CVSS v3 base score is 6.5 out of 10.

XXE in Alkacon Opencms

CVE-2021-3312

An XML external entity (XXE) vulnerability in Alkacon OpenCms 11.0, 11.0.1 and 11.0.2 allows remote authenticated users with edit privileges to exfiltrate files from the server's file system by uploading a crafted SVG document.

Vulnerability class: XXE (XML External Entity)

Published 2021-10-08 · last modified 2026-06-17.

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 (69.1th percentile), scored 2026-09-30.

Low probability of exploitation in the next 30 days, but still tracked. 69th percentile — 69.1% 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

Alkacon Opencms — versions 11.0, 11.0.1, 11.0.2

Weakness classification (CWE)

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

References

github.com/alkacon/opencms-core/releases (Third Party Advisory, Release Notes)
github.com/alkacon/opencms-core/issues/725 (Exploit, Third Party Advisory, Issue Tracking)

Frequently asked questions

What is CVE-2021-3312?: CVE-2021-3312 is a medium-severity vulnerability in Alkacon Opencms, classified under Improper Restriction of XML External Entity Reference (XXE). CVSS score: 6.5/10. Published 2021-10-08.
How severe is CVE-2021-3312?: Medium severity. CVSS v3 base score is 6.5 out of 10.