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CVE-2026-103877

Apache Directory LDAP API: Unsafe loading of Java code from LDAP schema elements

9.8 Critical

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
High

Exploit likelihood

0.47%Up 0.1 points since Oct 3, 2026
90%50%10%1%

What each source reports

CVE List Score used 9.8

Apache Directory LDAP API: Unsafe loading of Java code from LDAP schema elements

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.

Record
CVE-2026-103877
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-502
Updated
2026-11-02
EUVDEUVD-2026-91361 9.8

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.

Record
EUVD-2026-91361
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
GitHub AdvisoriesGHSA-v496-rffp-c5q7 9.8

Deserialization of Untrusted Data vulnerability in Apache Directory LDAP API. A rogue...

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.

Record
GHSA-v496-rffp-c5q7
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-502
Updated
2026-11-02
NVD 9.8

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.

Record
CVE-2026-103877
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-502
Updated
2026-11-02
OSVDEBIAN-CVE-2026-103877 9.8

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.

Record
DEBIAN-CVE-2026-103877
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2026-103877 9.8

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.

Record
UBUNTU-CVE-2026-103877
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
apache-directory-api
Debian:12
 All versions, plus listed versions
2.1.2-12.1.2-2
 None known
apache-directory-api
Debian:13
 All versions, plus listed versions
2.1.2-2
 None known
apache-directory-api
Debian:14
 All versions, plus listed versions
2.1.2-2
 None known
apache-directory-api
Ubuntu:16.04:LTS
 All versions, plus listed versions
1.0.0~M20-3
 None known
apache-directory-api
Ubuntu:18.04:LTS
 All versions, plus listed versions
1.0.0~M20-51.0.0-1
 None known
apache-directory-api
Ubuntu:20.04:LTS
 All versions, plus listed versions
1.0.0-1
 None known
apache-directory-api
Ubuntu:22.04:LTS
 All versions, plus listed versions
1.0.0-2
 None known
apache-directory-api
Ubuntu:24.04:LTS
 All versions, plus listed versions
2.1.2-1
 None known
apache-directory-api
Ubuntu:26.10
 All versions, plus listed versions
2.1.2-2build1
 None known
apache-directory-api
Ubuntu:26.04:LTS
 All versions, plus listed versions
2.1.2-22.1.2-2build1
 None known

History

History
RecordedChangedSources
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-103877 is a critical vulnerability (CVSS 9.8) in Apache Software Foundation Directory Ldap Api, published October 2, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.47%, the 40th percentile. No source names a fixed version.

References

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