What is CVE-2021-28684?

CVE-2021-28684 is a medium-severity vulnerability in Powerarchiver, classified under Improper Restriction of XML External Entity Reference (XXE). CVSS score: 4.3/10. Published 2021-06-21.

How severe is CVE-2021-28684?

Medium severity. CVSS v3 base score is 4.3 out of 10.

XXE in Powerarchiver

CVE-2021-28684

The XML parser used in ConeXware PowerArchiver before 20.10.02 allows processing of external entities, which might lead to exfiltration of local files over the network (via an XXE attack).

Vulnerability class: XXE (XML External Entity)

Published 2021-06-21 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N.

EPSS exploit prediction

EPSS: 0.009 (58.7th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 59th percentile — 58.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.009 · newest: 0.009 · change: 0.000

Affected products

Powerarchiver

Weakness classification (CWE)

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

References

www.powerarchiver.com (Product)
peterka.tech/blog/posts/cve-2021-28684/ (Exploit, Third Party Advisory)

Frequently asked questions

What is CVE-2021-28684?: CVE-2021-28684 is a medium-severity vulnerability in Powerarchiver, classified under Improper Restriction of XML External Entity Reference (XXE). CVSS score: 4.3/10. Published 2021-06-21.
How severe is CVE-2021-28684?: Medium severity. CVSS v3 base score is 4.3 out of 10.