---
id: CVE-2026-102731
title: >-
  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
summary: >-
  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…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-789
  - CWE-770
vendor: Apache Software Foundation
product: 'org.apache.directory.api:api-asn1-ber'
affected:
  - 'org.apache.directory.api:api-asn1-ber >= 1.2.0 < 1.2.9'
published: '2026-10-02'
updated: '2026-10-05'
sourceUpdated: '2026-10-05T19:17:12.740'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-102731'
references:
  - url: 'https://lists.apache.org/thread.html/b8kg8881pc0v8lp59w0fcfrs69wjbqvd'
    label: security@apache.org
  - url: 'http://www.openwall.com/lists/oss-security/2026/10/02/3'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-102731.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-102731'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2544985'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-102731'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-102731'
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-10-05T18:10:13.127732Z'
epss: 0.0043
epssPercentile: 0.37392
ingestedAt: '2026-10-02T10:15:55.904Z'
---

## Overview

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

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **Red Hat VEX** · Important · affected: Red Hat Fuse 7 · no fix planned: Red Hat Fuse 7 · updated 2026-10-05 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-102731.json)