CVE-2026-102731
Received Received - Intake

Memory Allocation DoS in Apache Directory LDAP API

Publication date: 2026-10-02

Last updated on: 2026-10-02

Assigner: Apache Software Foundation

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.

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Meta Information

Published
2026-10-02
Last Modified
2026-10-02
Generated
2026-10-02
AI Q&A
2026-10-02
EPSS Evaluated
N/A
NVD
CVE-2026-102731
EUVD
EUVD-2026-91333

Affected Vendors & Products

Showing 2 associated CPEs
Vendor Product Version / Range
apache directory_ldap_api to 1.2.9 (exc)
apache directory_ldap_api 1.2.9

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-789 The product allocates memory based on an untrusted, large size value, but it does not ensure that the size is within expected limits, allowing arbitrary amounts of memory to be allocated.

Attack-Flow Graph

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Executive Summary

This vulnerability involves a memory allocation issue in Apache Directory LDAP API where a malicious peer sends a small BER-encoded response that tricks the system into allocating a large amount of memory before receiving any data. This leads to an OutOfMemoryError and denial of service.

Detection Guidance

This vulnerability may cause OutOfMemoryError in the JVM or high memory usage per connection. Monitor Java processes for excessive memory consumption or crashes. Check LDAP client logs for decoder exceptions or stalled connections. No specific commands are provided in the context.

Impact Analysis

The vulnerability can cause denial of service by exhausting system memory. A few malicious connections can pin large memory allocations, crashing the JVM or freezing the server. This affects availability and stability of services using the vulnerable API.

Mitigation Strategies

Upgrade Apache Directory LDAP API to version 1.2.9 or later. Set MAX_PDU_SIZE_ATTR on embedding servers to limit PDU size. Restrict unauthenticated pre-bind client access to prevent malicious requests.

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