CVE-2026-102731

Apache Directory LDAP API: Denial of service via excessive memory allocation in BER decode

Published Oct 2, 2026 CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Weaknesses CWE-770
References
Metrics threat_severity

None

cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Important

Type Values Removed Values Added
First Time appeared Apache
Apache directory Ldap Api
Vendors & Products Apache
Apache directory Ldap Api
Type Values Removed Values Added
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.
Title Apache Directory LDAP API: Denial of service via excessive memory allocation in BER decode
Weaknesses CWE-789
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
apache
Published
Updated
Oct 5, 2026, 6:10 PM
Reserved
Sep 29, 2026, 4:17 PM
Status
Deferred
Published
Oct 2, 2026, 10:17 AM
Modified
Oct 5, 2026, 7:17 PM
Severity
Important
Public date
Oct 2, 2026, 9:22 AM