All vulnerabilities
CVE-2026-102731

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

Apache Software Foundation Apache Directory LDAP API
Open in ThreatlineRecord JSON
CVSS
7.5High
ExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)0.43%Chance of exploitation activity in the next 30 days, higher than 36% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in1.2.9Fixed versionCVE List
Published2 Oct 2026Updated 5 Oct 2026CVE List

What fixes it

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

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.

Text from CVE List

Affected versions 1

  • Apache Directory LDAP APIaffected: 1.2.0 before 1.2.9CVE List

References 1