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389 Directory Server CVE-2026-11793

| EUVDEUVD-2026-35423 MEDIUM
Stack-based Buffer Overflow (CWE-121)
2026-06-09 redhat GHSA-v6v5-66j3-444p
Buffer Overflow Denial Of Service Stack Overflow Red Hat Enterprise Linux 10 Red Hat Enterprise Linux 6 Red Hat Enterprise Linux 7 Red Hat Enterprise Linux 8 Red Hat Enterprise Linux 9 Red Hat Directory Server 11 Red Hat Directory Server 12 Red Hat Directory Server 13 Red Hat
4.9
CVSS 3.1 · Vendor: redhat
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Severity by source

Vendor (redhat) PRIMARY
4.9 MEDIUM
AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
SUSE
MEDIUM
qualitative
Red Hat
4.9 LOW
qualitative

Primary rating from Vendor (redhat).

CVSS VectorVendor: redhat

Attack Vector
Network
Attack Complexity
Low
Privileges Required
High
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

2
Analysis Generated
Jun 09, 2026 - 13:50 vuln.today
CVE Published
Jun 09, 2026 - 13:11 nvd
MEDIUM 4.9

DescriptionCVE.org

A stack buffer overflow flaw was found in 389 Directory Server. The checkPrefix() function in pw.c copies an attacker-controlled algorithm ID into a 256-byte stack buffer without bounds checking when parsing reversible-encrypted attribute values. An attacker with Directory Manager privileges can crash the LDAP server by storing a crafted credential with an oversized algorithm ID. FORTIFY_SOURCE mitigates this to denial of service only.

AnalysisAI

Stack buffer overflow in 389 Directory Server's pw.c checkPrefix() function allows a network-accessible Directory Manager to crash the LDAP server by storing a crafted credential with an oversized algorithm ID. The vulnerable code copies attacker-controlled input into a fixed 256-byte stack buffer without bounds checking when parsing reversible-encrypted attribute values. FORTIFY_SOURCE compiler hardening constrains impact to denial of service - preventing arbitrary code execution - but service disruption against a critical authentication infrastructure component remains operationally significant. No public exploit identified at time of analysis.

Technical ContextAI

The flaw resides in the checkPrefix() function in pw.c within the 389 Directory Server codebase, which is the upstream project for Red Hat Directory Server (RHDS) 11, 12, and 13. CWE-121 (Stack-based Buffer Overflow) is the root cause: the function performs an unbounded copy of an attacker-supplied algorithm identifier string - derived from a stored reversible-encrypted attribute value - into a 256-byte stack-allocated buffer. Any algorithm ID exceeding 256 bytes overflows the stack frame. The FORTIFY_SOURCE compile-time protection detects the out-of-bounds write at runtime and aborts the process rather than allowing a controlled write-what-where primitive, which is why code execution is not achievable and the impact is limited to A:H (availability only). Affected CPEs span RHDS 11/12/13 (cpe:2.3:a:red_hat:red_hat_directory_server_11/12/13) and the bundled 389-ds package across RHEL 6 through 10.

RemediationAI

Patch available per vendor advisory, but no exact fixed version is confirmed in the provided input data - consult https://access.redhat.com/security/cve/CVE-2026-11793 directly and apply the errata package when Red Hat releases it via their normal RHSA process. As a compensating control prior to patching, restrict the Directory Manager DN to a minimal set of trusted administrative hosts using LDAP access control instructions (ACIs) or firewall rules limiting port 389/636 access to known management IPs - this does not eliminate the vulnerability but removes network reachability for untrusted parties. Additionally, audit which accounts hold Directory Manager-equivalent privileges and reduce that set to the minimum necessary; this limits who can trigger the flaw. Disabling reversible password encryption (if not operationally required) would remove the attack surface entirely, but note this is a breaking change for applications relying on password retrieval. Do not rely solely on FORTIFY_SOURCE as a permanent mitigation - it is a hardening layer, not a fix.

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Vendor StatusVendor

SUSE

Severity: Moderate
Product Status
SUSE Linux Enterprise High Performance Computing 15 SP7 Affected
SUSE Linux Enterprise Module for Server Applications 15 SP7 Affected
SUSE Linux Enterprise Server 15 SP7 Affected
SUSE Linux Enterprise Server 16.0 Affected
SUSE Linux Enterprise Server 16.1 Affected

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CVE-2026-11793 vulnerability details – vuln.today
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