CVE intelligence and bounded remediation

CVE-2021-40874 — An issue was discovered in LemonLDAP::NG (aka lemonldap-ng) 2.0.13

Critical CVSS 9.8

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.

Severity
Critical
CVSS
9.8 (3.1)
Published
2022-07-18
CISA KEV
Not currently listed
Ecosystem
software/application
Weaknesses
CWE-287

Affected products

  • lemonldap-ng / lemonldap::ng / 2.0.13
  • debian / debian_linux / 10.0

Matched remediation archetype

Authentication bypass and missing authentication

This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.

Check exposure

  • Map every affected endpoint and protocol path, including alternate ports, legacy routes, recovery flows, service accounts, and machine-to-machine access.
  • Confirm which deployments enable the affected authentication mode and whether the interface is reachable from untrusted networks.
  • Review session, token, credential, and proxy trust configuration without attempting account takeover.

Remediate safely

  • Apply the supported fix and centralize fail-closed authentication before protected request handling.
  • Remove default or embedded credentials, rotate affected secrets and sessions, and bind authentication decisions to the intended audience and channel.
  • Add negative tests for alternate routes, malformed or absent credentials, recovery flows, and proxy-derived identity.

Authoritative sources

Complete CVE record and remediation plan

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