Vulnerability · Published Oct 2, 2026 · Assigned by apache
CVE-2026-102731Apache Directory LDAP API: Denial of service via excessive memory allocation in BER decode
High 7.5
In plain English
A high-severity security flaw in Apache Directory LDAP API from Apache Software Foundation. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 37% of all known vulnerabilities).
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | apache-directory-api | no fix listed | DEBIAN-CVE-2026-102731 |
| Debian:13 | apache-directory-api | no fix listed | DEBIAN-CVE-2026-102731 |
| Debian:14 | apache-directory-api | no fix listed | DEBIAN-CVE-2026-102731 |
| Ubuntu:22.04:LTS | apache-directory-api | no fix listed | UBUNTU-CVE-2026-102731 |
| Ubuntu:24.04:LTS | apache-directory-api | no fix listed | UBUNTU-CVE-2026-102731 |
| Ubuntu:26.04:LTS | apache-directory-api | no fix listed | UBUNTU-CVE-2026-102731 |
| Ubuntu:26.10 | apache-directory-api | no fix listed | UBUNTU-CVE-2026-102731 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Apache Software Foundation | Apache Directory LDAP API | 1.2.0 – before 1.2.9 |
Weakness: CWE-789 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H