CVE-2026-103877: Apache Directory LDAP API: Unsafe loading of Java code from LDAP schema elements

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-02 · updated 2026-10-07
Weakness: CWE-502

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.

Affected products

Apache Software Foundation Apache Directory LDAP API: from 2.1.0 before 2.1.9 — fixed in 2.1.9

How to fix

Upgrade to a fixed version: Apache Software Foundation Apache Directory LDAP API 2.1.9. Check the vendor advisory for mitigations.

References

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