CVE-2023-2953

What it actually does

Null pointer dereference in ber_memalloc_x() causes the OpenLDAP server process to crash, resulting in denial of service.

Why it matters to the business

Interruption of directory, authentication, and lookup services across many enterprise and infrastructure products, leading to operational downtime.

How an attack unfolds

An unauthenticated attacker sends a crafted network request that reaches the vulnerable ber_memalloc_x call path, triggering the dereference and immediate process termination.

How to fix it

Upgrade OpenLDAP and all affected products (Red Hat Enterprise Linux, Apple macOS, NetApp ONTAP and related tools) to patched releases as they become available from each vendor; apply vendor-specific fixes promptly.

How to confirm the fix worked

Confirm updated package versions are installed, review changelogs for the ber_memalloc_x fix, and perform controlled availability tests with known triggering inputs.

Typical attack path

1. Identify exposed OpenLDAP or dependent service
2. Send crafted LDAP protocol message over the network
3. Trigger null pointer dereference in ber_memalloc_x
4. Server process crashes, denying service to legitimate users

How to detect it

Search OpenLDAP and system logs for segmentation faults, crashes, or stack traces referencing ber_memalloc_x; correlate with sudden service restarts or availability alerts.

• ber_memalloc_x
• null pointer dereference
• ldap server segmentation fault
• slapd crash

What your security team should do

• Prioritize patching OpenLDAP instances and downstream products due to broad ecosystem exposure
• Restrict unauthenticated network access to LDAP ports where feasible
• Enable process monitoring and automatic restart for directory services
• Track vendor advisories for fixed versions across listed products