What is CVE-2021-44556?

CVE-2021-44556 is a critical-severity vulnerability in Kb Digger, classified under Improper Restriction of XML External Entity Reference (XXE). CVSS score: 9.1/10. Published 2021-12-08.

How severe is CVE-2021-44556?

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

XXE in Kb Digger

CVE-2021-44556

National Library of the Netherlands digger < 6697d1269d981e35e11f240725b16401b5ce3db5 is affected by a XML External Entity (XXE) vulnerability. Since XML parsing resolves external entities, a malicious XML stream could leak internal files and/or cause a DoS.

Vulnerability class: XXE (XML External Entity)

Published 2021-12-08 · 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: 0.013 (69.5th percentile), scored 2026-10-04.

Low probability of exploitation in the next 30 days, but still tracked. 70th percentile — 69.5% 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

Kb Digger

Weakness classification (CWE)

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

References

github.com/KBNLresearch/digger (Product, Third Party Advisory)
github.com/KBNLresearch/digger/pull/1 (Patch, Third Party Advisory)

Frequently asked questions

What is CVE-2021-44556?: CVE-2021-44556 is a critical-severity vulnerability in Kb Digger, classified under Improper Restriction of XML External Entity Reference (XXE). CVSS score: 9.1/10. Published 2021-12-08.
How severe is CVE-2021-44556?: Critical severity. CVSS v3 base score is 9.1 out of 10.