CVE-2025-2487 Overview
A null pointer dereference vulnerability has been identified in the 389-ds-base LDAP Server. This security flaw occurs when issuing a Modify DN (MODDN) LDAP operation through the LDAP protocol, specifically when the function return value is not properly validated, leading to a NULL pointer being dereferenced. When a privileged user performs an LDAP MODDN operation following a failed operation, the vulnerability can be triggered, resulting in a Denial of Service (DoS) condition or complete system crash.
Critical Impact
Privileged attackers can exploit this NULL pointer dereference to crash the 389 Directory Server, causing service disruption and potential downtime for dependent authentication and directory services.
Affected Products
- 389-ds-base LDAP Server
- Red Hat Directory Server
- Red Hat Enterprise Linux (versions using 389-ds-base)
Discovery Timeline
- 2025-03-18 - CVE-2025-2487 published to NVD
- 2025-05-13 - Last updated in NVD database
Technical Details for CVE-2025-2487
Vulnerability Analysis
This vulnerability is classified as CWE-476 (NULL Pointer Dereference), a memory corruption flaw that occurs when the application attempts to use a pointer that is expected to be valid but is actually NULL. In the context of 389-ds-base, the flaw manifests within the LDAP Modify DN operation handler, where error conditions from a previous failed operation leave the system in an inconsistent state.
The vulnerability requires privileged access to exploit, meaning an attacker must first authenticate as a privileged user with permissions to perform MODDN operations. While this raises the bar for exploitation, it represents a significant risk in environments where directory service availability is critical to authentication infrastructure.
Root Cause
The root cause of this vulnerability is improper error handling in the LDAP MODDN operation processing code. Specifically, when an LDAP operation fails, the function return value is not properly checked before subsequent pointer operations. This missing validation allows a NULL pointer to be dereferenced when a privileged user initiates a MODDN operation following a failed operation sequence.
The flaw represents a classic defensive programming oversight where return value validation was omitted, leading to undefined behavior when the code path encounters an unexpected NULL value.
Attack Vector
The attack is conducted over the network via the LDAP protocol. An attacker with privileged access to the 389 Directory Server can trigger the vulnerability by executing a specific sequence of LDAP operations:
- The attacker authenticates to the LDAP server with privileged credentials
- An LDAP operation is executed that results in a failure condition
- Immediately following the failed operation, the attacker issues a Modify DN (MODDN) request
- The MODDN handler attempts to use a pointer that was not properly initialized due to the previous failure, causing a NULL pointer dereference
- The server process crashes, resulting in denial of service
The vulnerability does not allow code execution or data exfiltration—the impact is limited to availability through service disruption.
Detection Methods for CVE-2025-2487
Indicators of Compromise
- Unexpected 389 Directory Server (ns-slapd) process crashes or restarts
- LDAP service unavailability following authenticated MODDN operations
- Core dumps or crash logs indicating NULL pointer access in MODDN-related functions
- Patterns of failed LDAP operations immediately followed by MODDN requests from the same connection
Detection Strategies
- Monitor system logs for ns-slapd segmentation faults or crash events related to LDAP operations
- Implement LDAP access logging to track MODDN operations from privileged accounts
- Configure process monitoring to alert on unexpected directory server restarts
- Review authentication logs for unusual privileged account activity patterns
Monitoring Recommendations
- Enable detailed LDAP access logging on 389-ds-base servers to capture operation sequences
- Configure system monitoring tools to detect ns-slapd process crashes and automatic restart events
- Implement baseline monitoring for normal LDAP operation patterns to identify anomalous MODDN activity
- Set up alerts for repeated directory service failures or availability issues
How to Mitigate CVE-2025-2487
Immediate Actions Required
- Apply the latest security patches from Red Hat as referenced in the security advisories
- Review and restrict privileged access to LDAP MODDN operations to only essential accounts
- Implement network segmentation to limit LDAP server exposure to trusted networks only
- Monitor for signs of exploitation while planning patch deployment
Patch Information
Red Hat has released security advisories addressing this vulnerability. Organizations running affected versions of 389-ds-base should apply the appropriate patches:
- Red Hat Security Advisory RHSA-2025:3663
- Red Hat Security Advisory RHSA-2025:3670
- Red Hat Security Advisory RHSA-2025:4491
- Red Hat Security Advisory RHSA-2025:7395
Additional details are available in the Red Hat CVE Details for CVE-2025-2487 and Red Hat Bug Report #2353071.
Workarounds
- Restrict LDAP MODDN operation privileges to only essential administrative accounts until patches can be applied
- Implement additional access controls at the network level to limit who can connect to the LDAP service
- Enable high-availability or failover configurations to maintain directory service availability in case of crashes
- Consider implementing rate limiting on LDAP connections from individual clients to slow potential exploitation attempts
# Example: Review and audit privileged LDAP access
# List users with MODDN permissions in 389-ds-base
ldapsearch -x -H ldap://localhost -D "cn=Directory Manager" -W \
-b "cn=config" "(objectClass=nsBackendInstance)" aci
# Enable detailed access logging for MODDN operations
dsconf localhost backend config set --nsslapd-auditlog-logging-enabled on
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
