Apache Directory security advisories

Security information for Apache Directory

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Advisories

This section is experimental: it provides advisories since 2023 and may lag behind the official CVE publications. It may also lack details found on the project security pages linked above. If you have any feedback on how you would like this data to be provided, you are welcome to reach out on our public mailinglist or privately on security@apache.org

Kerberos Pre-Authentication Bypass

CVE-2026-57915 [CVE] [CVE json] [OSV json]

Last updated: 2026-06-26T12:09:53.178Z

Affected

  • Apache Kerby before 2.1.2

Description

It is possible to bypass the Kerberos pre-authentication check in Apache Kerby by sending a PA-DATA with an unrecognized or unsupported type. Users are recommended to upgrade to version 2.1.2, which fixes this issue.

References

StackOverflow on parsing deeply nested ASN1 structures

CVE-2026-57914 [CVE] [CVE json] [OSV json]

Last updated: 2026-06-26T11:28:25.784Z

Affected

  • Apache Kerby before 2.1.2

Description

By sending a deeply nested ASN1 structure to a Apache Kerby client or service, it’s possible to trigger a StackOverFlow Exception which can lead to denial of service issues. Users are recommended to upgrade to version 2.1.2, which fixes this issue.

References

LDAP client implementation does not verify if the server certificate matches the intended LDAP hostname

CVE-2026-35563 [CVE] [CVE json] [OSV json]

Last updated: 2026-06-01T07:38:34.650Z

Affected

  • Apache Directory LDAP API from 2.0.0 through 2.1.7

Description

It was identified that the LDAP client implementation in version 2.1.7 does not verify if the server certificate matches the intended LDAP hostname. While the underlying code validates the certificate chain against a trusted authority, the absence of endpoint identification allows a valid certificate issued for an entirely unrelated host to be improperly accepted. This oversight leaves the connection highly vulnerable to server impersonation and complete connection compromise.


The root cause of this vulnerability lies in the incomplete TLS server identity verification within the LDAP client implementation.

The attacker requires MITM capability on the network to exploit this vulnerability. This attacker must be able to present a certificate trusted by the client’s configured trust store.

The hostname verification has been enforced in the new version of the LDAP API

References

Credits

  • Rafał Łykowski and Łukasz Kollbek of Qualtrics (finder)

Denial of service via crafted telephone number values

CVE-2026-103885 [CVE] [CVE json] [OSV json]

Last updated: 2026-10-02T10:09:46.664Z

Affected

  • Apache Directory LDAP API from 2.1.0 before 2.1.9

Description

Asymmetric Resource Consumption vulnerability in Apache Directory LDAP API.

A LDAP server using the LDAP API (like Apache DS) may consume 100% of a CPU core indefinitely when processing some badly crafted Telephone Numbers.

This issue affects Apache Directory LDAP API: from 2.1.0 before 2.1.9.

Users are recommended to upgrade to version 2.1.9, which fixes the issue.

References

Credits

  • Claude Security (tool)
  • The Apache Software Foundation (finder)

Denial of service via excessive bcrypt cost factor in stored passwords

CVE-2026-103880 [CVE] [CVE json] [OSV json]

Last updated: 2026-10-02T10:03:42.918Z

Affected

  • Apache Directory LDAP API from 2.1.0 before 2.1.9

Description

Asymmetric Resource Consumption vulnerability in Apache Directory LDAP API.

Storing a password using the bcrypt algorithm with a high force like 30 in a LDAP server that supports this algorithm will cause the server CPU to  run for hours checking the credentials. A bounded cost should be enforced to avoid a server DOS.

This issue affects Apache Directory LDAP API: from 2.1.0 before 2.1.9.

Users are recommended to upgrade to version 2.1.9, which fixes the issue.

References

Credits

  • Claude Security (tool)
  • The Apache Software Foundation (finder)

Injection of plaintext responses during StartTLS

CVE-2026-103878 [CVE] [CVE json] [OSV json]

Last updated: 2026-10-02T10:02:31.520Z

Affected

  • Apache Directory LDAP API from 2.1.0 before 2.1.9

Description

Cleartext transmission of sensitive information vulnerability in Apache Directory LDAP API.

A StartTLS extended operation started after a Search request has been sent can lead to receive data in plain text before the TLS Handshake has been completed.

This issue affects Apache Directory LDAP API: from 2.1.0 before 2.1.9.

Users are recommended to upgrade to version 2.1.9, which fixes the issue.

References

Credits

  • Claude Security (tool)
  • The Apache Software Foundation (finder)

Unsafe loading of Java code from LDAP schema elements

CVE-2026-103877 [CVE] [CVE json] [OSV json]

Last updated: 2026-10-02T10:08:30.840Z

Affected

  • Apache Directory LDAP API from 2.1.0 before 2.1.9

Description

Deserialization of Untrusted Data vulnerability in Apache Directory LDAP API.

A rogue/compromised LDAP server (or pre-TLS MITM) can answer a client's loadSchema() subschema search with a schema object that contains a serialized Java class, allowing some potential RCE. 

This issue affects Apache Directory LDAP API: from 2.1.0 before 2.1.9.

Users are recommended to upgrade to version 2.1.9, which fixes the issue.

References

Credits

  • Claude Security (tool)
  • The Apache Software Foundation (finder)

A unbound client can send a deeply nested search filter that overflows the stack in the server’s decoder

CVE-2026-103552 [CVE] [CVE json] [OSV json]

Last updated: 2026-10-02T09:47:58.183Z

Affected

  • Apache Directory LDAP API from 1.2.0 before 1.2.9

Description

Stack Overflow vulnerability in Apache Directory LDAP API.

Before binding, a client can send a deeply nested search filter that overflows the stack in the server's decoder.

This issue affects Apache Directory LDAP API: from 1.2.0 before 1.2.9.

Users are recommended to upgrade to version 1.2.9, which fixes the issue.

References

Credits

  • Claude Security (tool)
  • The Apache Software Foundation (finder)

Denial of service via excessive memory allocation in BER decode

CVE-2026-102731 [CVE] [CVE json] [OSV json]

Last updated: 2026-10-02T09:21:56.550Z

Affected

  • Apache Directory LDAP API from 1.2.0 before 1.2.9

Description

Memory allocation with excessive size value vulnerability in Apache Directory LDAP API.

A malicious peer (or a MITM) can send a small BER-encoded response causing a large memory allocation before any data is received. This can lead to an OutOfMemoryError and denial of service.

The client JVM OOMs (OutOfMemoryError bypasses the DecoderException handlers) or pins the large allocation per connection while the attacker stalls.

A handful of connections exhausts any heap. The same bytes from an unauthenticated pre-bind client hit any embedding server that did not set MAX_PDU_SIZE_ATTR.

This issue affects Apache Directory LDAP API: from 1.2.0 before 1.2.9.

Users are recommended to upgrade to version 1.2.9, which fixes the issue.

References

Credits

  • Claude Security (tool)
  • The Apache Software Foundation (finder)

LDAP Injection Vulnerability in Apache Kerby

CVE-2023-25613 [CVE] [CVE json] [OSV json]

Last updated: 2024-01-18T09:14:01.669Z

Affected

  • Apache Kerby LDAP Backend before 2.0.3

Description

An LDAP Injection vulnerability exists in the LdapIdentityBackend of Apache Kerby before 2.0.3. 

References

Credits

  • 4ra1n of Chaitin Tech (finder)

StartTLS and SASL confidentiality protection bypass

CVE-2021-33900 [CVE] [CVE json] [OSV json]

Last updated: 2021-07-26T07:00:11.196Z

Affected

  • Apache Directory Studio from unspecified through 2.0.0.v20210213-M16

Description

While investigating DIRSTUDIO-1219 it was noticed that configured StartTLS encryption was not applied when any SASL authentication mechanism (DIGEST-MD5, GSSAPI) was used. While investigating DIRSTUDIO-1220 it was noticed that any configured SASL confidentiality layer was not applied. This issue affects Apache Directory Studio version 2.0.0.v20210213-M16 and prior versions.

References

Credits

  • Apache Directory would like to thank Hugh Cole-Baker for reporting this issue.