How severe is CVE-2021-40874?

CVE-2021-40874 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-40874 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (56th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-40874?

CVE-2021-40874 primarily affects Lemonldap-ng Lemonldap. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-40874?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2021-40874 published?

CVE-2021-40874 was published on 2022-07-18 and last updated on 2026-06-17.

CVE-2021-40874

CVE-2021-40874 is a critical-severity vulnerability in Lemonldap-ng Lemonldap with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-287.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
EPSS exploit prediction: 1% (56th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-287
Affected product: Lemonldap-ng Lemonldap
Published: 2022-07-18
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is 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.
How severe is CVE-2021-40874?: CVE-2021-40874 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-40874 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (56th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-40874?: CVE-2021-40874 primarily affects Lemonldap-ng Lemonldap. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-40874?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2021-40874 published?: CVE-2021-40874 was published on 2022-07-18 and last updated on 2026-06-17.

References

https://gitlab.ow2.org/lemonldap-ng/lemonldap-ng/-/issues/2612

Affected products (2)

cpe:2.3:a:lemonldap-ng:lemonldap\:\:ng:2.0.13:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*

Other CWE-287 (Improper Authentication) vulnerabilities

CVE-2026-45480 — Critical (CVSS 10.0): Improper authentication in Azure Active Directory allows an unauthorized attacker to elevate privileges over a network.
CVE-2026-46389 — Critical (CVSS 10.0): UDS Identity Config builds the Keycloak configuration image (realm, plugins, theme, truststore, JARs) consumed by UDS…
CVE-2026-10611 — Critical (CVSS 10.0): An authentication bypass vulnerability exists in MISP when LDAP mixed authentication is enabled with OTP enforcement.…
CVE-2026-47280 — Critical (CVSS 10.0): Improper authentication in Azure Resource Manager (ARM) allows an unauthorized attacker to elevate privileges over a…
CVE-2026-42822 — Critical (CVSS 10.0): Improper authentication in Azure Local Disconnected Operations allows an unauthorized attacker to elevate privileges…
CVE-2026-20182 — Critical (CVSS 10.0): May 2026: This security advisory provides the details and fix information for a vulnerability that was discovered and…

Browse all CWE-287 (Improper Authentication) vulnerabilities →