What is CVE-2021-40874?

CVE-2021-40874 is a critical-severity vulnerability in Lemonldap-Ng Lemonldap\, classified under Improper Authentication. CVSS score: 9.8/10. Published 2022-07-18.

How severe is CVE-2021-40874?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Auth bypass in Lemonldap-Ng Lemonldap\

CVE-2021-40874

An issue was discovered in LemonLDAP::NG (aka lemonldap-ng) 2.0.13. When using the RESTServer plug-in to operate a REST password validation service (for another LemonLDAP::NG instance, for example) and using the Kerberos authentication method combined with another method with the Combination authentication plug-in, any password will be recognized as valid for an existing user.

Vulnerability class: Broken Authentication

Published 2022-07-18 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.012 (65.7th percentile), scored 2026-09-30.

Low probability of exploitation in the next 30 days, but still tracked. 66th percentile — 65.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.011 · newest: 0.012 · change: +0.001

Affected products

Lemonldap-Ng Lemonldap\ — versions \
Lemonldap-Ng Lemonldap\:\:ng — versions 2.0.13
Debian Linux — versions 10.0

Weakness classification (CWE)

CWE-287 — Improper Authentication

References

gitlab.ow2.org/lemonldap-ng/lemonldap-ng/-/issues/2612 (Exploit, Patch, Third Party Advisory, Issue Tracking)

Frequently asked questions

What is CVE-2021-40874?: CVE-2021-40874 is a critical-severity vulnerability in Lemonldap-Ng Lemonldap\, classified under Improper Authentication. CVSS score: 9.8/10. Published 2022-07-18.
How severe is CVE-2021-40874?: Critical severity. CVSS v3 base score is 9.8 out of 10.