Apache Directory LDAP API up to 1.2.8 Decoder allocation of resources

Summaryinfo

A vulnerability labeled as problematic has been found in Apache Directory LDAP API up to 1.2.8. The impacted element is an unknown function of the component Decoder. Such manipulation leads to allocation of resources. This vulnerability is traded as CVE-2026-102731. The attack may be launched remotely. There is no exploit available. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in Apache Directory LDAP API up to 1.2.8 and classified as problematic. Affected by this issue is an unknown part of the component Decoder. The manipulation with an unknown input leads to a allocation of resources vulnerability. Using CWE to declare the problem leads to CWE-770. The product allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on the size or number of resources that can be allocated, in violation of the intended security policy for that actor. Impacted is availability. CVE summarizes:

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.

The advisory is shared for download at lists.apache.org. This vulnerability is handled as CVE-2026-102731 since 09/29/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. There are neither technical details nor an exploit publicly available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 10/02/2026). The MITRE ATT&CK project declares the attack technique as T1499.

Upgrading to version 1.2.9 eliminates this vulnerability.

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Productinfo

Type

• Directory Service Software

Vendor

• Apache

Name

• Directory LDAP API

Version

• 1.2.0
• 1.2.1
• 1.2.2
• 1.2.3
• 1.2.4
• 1.2.5
• 1.2.6
• 1.2.7
• 1.2.8

License

• open-source

Website

• Vendor: https://www.apache.org/

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