CVE-2026-16560
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Heap-Buffer-Overflow in 389 Directory Server

Publication date: 2026-07-22

Last updated on: 2026-07-22

Assigner: Red Hat, Inc.

Description
A heap-buffer-overflow flaw was found in Directory Server (389-ds-base). When a DN contains a legacy-quoted value, the server won't close the heap allocation allowing another call to refer to the same memory pointer causing a denial of service or an arbitrary memory write operation.

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Meta Information

Published
2026-07-22
Last Modified
2026-07-22
Generated
2026-07-22
AI Q&A
2026-07-22
EPSS Evaluated
N/A
NVD
CVE-2026-16560
EUVD
EUVD-2026-47661

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
redhat 389_directory_server *

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-1220 The product implements access controls via a policy or other feature with the intention to disable or restrict accesses (reads and/or writes) to assets in a system from untrusted agents. However, implemented access controls lack required granularity, which renders the control policy too broad because it allows accesses from unauthorized agents to the security-sensitive assets.

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Executive Summary

CVE-2026-16560 is a heap-buffer-overflow vulnerability in the 389 Directory Server (389-ds-base). It occurs when processing a multivalued nested Relative Distinguished Name (RDN) with quoted values, such as 'cn=a+sn=b',dc=com. The parser fails to finalize tracking of nested Attribute-Value pairs when encountering a closing quote, leading to incorrect memory handling and potential memory corruption.

Detection Guidance

Monitor for crashes or memory corruption in 389 Directory Server processes. Check logs for malformed DN entries with quoted values like cn=a+sn=b. Use tools like valgrind or AddressSanitizer to detect heap-buffer-overflows during DN parsing.

Impact Analysis

This vulnerability can cause a denial of service or an arbitrary memory write operation. Attackers could exploit it to crash the server or execute arbitrary code, potentially leading to system compromise or data breaches.

Compliance Impact

This vulnerability could potentially impact compliance with GDPR and HIPAA by enabling denial of service or arbitrary memory write operations. A heap-buffer-overflow may lead to service disruption or unauthorized data access, which are critical risks under these regulations.

Mitigation Strategies

Update 389-ds-base to the latest patched version. Avoid using legacy-quoted values in DNs. Restrict network access to the Directory Server until patched. Monitor for exploitation attempts targeting DN parsing.

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