CVE-2026-11785: 389 Directory Server Information Disclosure

CVE-2026-11785 Overview

A type confusion vulnerability exists in the 389 Directory Server, an enterprise-class Lightweight Directory Access Protocol (LDAP) server maintained by Red Hat. The flaw resides in the Single Sign-On (SSO) token extended operation handler, where improper type handling causes the server to disclose partial stack address information in LDAP responses. Authenticated users can trigger this condition and receive leaked memory address data through standard LDAP responses. The disclosed addresses can assist attackers in bypassing Address Space Layout Randomization (ASLR) protections, enabling more reliable exploitation of memory corruption vulnerabilities. The weakness is classified under [CWE-843: Access of Resource Using Incompatible Type (Type Confusion)].

Critical Impact
Authenticated LDAP users can extract partial stack address information from server memory, weakening ASLR defenses and aiding follow-on memory exploitation.

Affected Products

389 Directory Server (upstream project)
Red Hat Directory Server distributions tracking the affected SSO token handler
Downstream LDAP deployments incorporating the vulnerable extended operation handler

Discovery Timeline

2026-06-09 - CVE-2026-11785 published to the National Vulnerability Database (NVD)
2026-06-09 - Last updated in NVD database

Technical Details for CVE-2026-11785

Vulnerability Analysis

The vulnerability stems from a type confusion condition within the SSO token extended operation handler in 389 Directory Server. Extended operations in LDAP allow clients to invoke server-defined functionality beyond the base protocol. When the SSO token handler processes a request, it interprets a memory region as the wrong data type during response construction. This mismatch causes the server to include uninitialized or adjacent stack memory in the response payload returned to the client. The leaked bytes contain partial stack address information, which exposes pointers from the running server process. Exploitation requires only valid LDAP credentials and standard network access to the directory service, making the flaw reachable in any environment where authenticated bind operations succeed.

Root Cause

The root cause is incorrect type handling [CWE-843] in the SSO token extended operation code path. The handler treats one structure as another during response serialization, causing the server to read beyond the intended data boundary. Stack-resident pointers are then copied into the LDAP response sent back to the client.

Attack Vector

An authenticated attacker issues a crafted LDAP extended operation request targeting the SSO token handler. The server responds with output containing partial stack addresses. The attacker correlates the leaked addresses to defeat ASLR and prepare exploitation of secondary memory corruption issues in the same process.

No verified public exploit code is available. See the Red Hat CVE Advisory and the Red Hat Bug Report for technical details.

Detection Methods for CVE-2026-11785

Indicators of Compromise

LDAP extended operation requests targeting the SSO token OID from authenticated clients that do not normally invoke SSO flows
Unusual volume of extended operation requests originating from a single authenticated principal
LDAP response payloads of anomalous size returned by the SSO token handler

Detection Strategies

Enable verbose LDAP access logging on 389 Directory Server and review entries for the SSO token extended operation OID
Correlate authenticated bind events with subsequent extended operation calls to identify reconnaissance patterns
Apply network-layer inspection on port 389/636 to flag repeated extended operation requests from non-SSO client populations

Monitoring Recommendations

Forward 389 Directory Server access and error logs to a centralized SIEM for retention and correlation
Alert on authenticated principals issuing extended operations outside documented application behavior
Track baseline LDAP response sizes per operation type and flag statistical outliers tied to the SSO handler

How to Mitigate CVE-2026-11785

Immediate Actions Required

Identify all 389 Directory Server and Red Hat Directory Server instances in the environment and confirm version exposure
Restrict LDAP access to trusted application accounts and management subnets until patches are applied
Audit existing service accounts and revoke unused or overly privileged bind credentials that could be abused to trigger the handler

Patch Information

Monitor the Red Hat CVE Advisory and the Red Hat PSIRT Tracking ticket for fixed package versions. Apply vendor-supplied updates to the 389-ds-base package as they become available through standard distribution channels.

Workarounds

Disable the SSO token extended operation handler if the deployment does not require SSO token functionality
Enforce strict access control instructions (ACIs) to limit which authenticated users may invoke extended operations
Place the directory server behind a network segment that limits LDAP exposure to authorized application hosts only

bash

# Example: restrict LDAP exposure at the host firewall to known application subnets
# Replace 10.0.0.0/24 with your authorized client subnet
firewall-cmd --permanent --zone=public --remove-service=ldap
firewall-cmd --permanent --zone=public --remove-service=ldaps
firewall-cmd --permanent --new-zone=ldap-trusted
firewall-cmd --permanent --zone=ldap-trusted --add-source=10.0.0.0/24
firewall-cmd --permanent --zone=ldap-trusted --add-service=ldaps
firewall-cmd --reload