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CVE Record

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

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.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

This flaw affects LemonLDAP::NG 2.0.13 in a specific password-validation setup. If RESTServer is used with Kerberos and Combination authentication, an existing user's password may be accepted regardless of the password entered. That can undermine authentication for connected services using that validation flow.

Executive priority

Prioritize review if LemonLDAP::NG supports business authentication or single sign-on. Matching systems may accept invalid passwords for existing users, creating a meaningful access-control risk even though exploitation evidence is not provided.

Technical view

The reported condition is an authentication validation failure in LemonLDAP::NG 2.0.13. With RESTServer operating as a REST password validation service, Kerberos authentication combined with another method through the Combination plugin may cause any password to validate for an existing user.

Likely exposure

Exposure appears limited to LemonLDAP::NG 2.0.13 deployments using RESTServer for password validation with Kerberos plus Combination authentication. The source bundle does not identify other versions, products, or default exposure.

Exploitation context

The bundle provides no KEV listing and no cited evidence of active exploitation. The issue could be serious in matching configurations because it affects authentication, but the available evidence does not include exploit maturity, public exploit activity, or attack prevalence.

Researcher notes

The available CVE data is narrow: one affected version, one configuration pattern, no CVSS, no CWE, and no named fix in the supplied bundle. Treat scope and remediation as vendor-guidance dependent.

Mitigation direction

  • Check the LemonLDAP::NG issue and vendor guidance for fixed versions or workarounds.
  • Inventory LemonLDAP::NG 2.0.13 systems using RESTServer password validation.
  • Avoid the described Kerberos plus Combination authentication configuration until vendor guidance is applied.
  • Document affected instances and track remediation against LemonLDAP::NG guidance.

Validation and detection

  • Review LemonLDAP::NG version data for 2.0.13 deployments.
  • Check whether RESTServer is configured as a password validation service.
  • Verify whether Kerberos is combined with another method through the Combination plugin.
  • Confirm which downstream services rely on that password validation path.
Prepared
Confidence
medium
Sources
3

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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ATT&CK lookup starting points

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description · low confidence lookup

Credential and access behavior lookup

The CVE wording references authentication or credential exposure, so valid-account and credential-access review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

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cve · low confidence lookup

CVE-2021-40874 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
0Timeline events
0ADP providers
2Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/an/an/aListed
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.