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389 Directory Server CVE-2026-12528

MEDIUM
Out-of-bounds Write (CWE-787)
2026-06-17 redhat
Buffer Overflow Memory Corruption 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
5.4
CVSS 3.1 · NVD
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Severity by source

Vendor (redhat) PRIMARY
MEDIUM
qualitative
NVD
5.4 MEDIUM
AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L
vuln.today AI
5.4 MEDIUM

Network-reachable LDAP with low-privilege aci-write access required; heap corruption yields only limited integrity and availability impact with no confidentiality breach.

3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L
4.0 AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N
SUSE
MEDIUM
qualitative
Red Hat
5.4 LOW
qualitative

Primary rating from Vendor (redhat).

CVSS VectorNVD

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

Lifecycle Timeline

3
Source Code Evidence Fetched
Jun 17, 2026 - 15:40 vuln.today
Analysis Generated
Jun 17, 2026 - 15:40 vuln.today
CVE Published
Jun 17, 2026 - 14:27 cve.org
MEDIUM 5.4

DescriptionNVD

A flaw was found in 389 Directory Server in the __aclp__normalize_acltxt() function of aclparse.c. A malformed ACI (Access Control Instruction) string can trigger heap-buffer-overflow writes and reads during ACI parsing. The function fails to validate that the ACI keyword has sufficient length after whitespace stripping, leading to a 1-byte out-of-bounds write and subsequent out-of-bounds reads. An authenticated user with write access to the aci attribute could send a crafted ACI value to silently corrupt heap memory in the directory server process.

AnalysisAI

Heap buffer overflow in 389 Directory Server's ACI parsing layer allows an authenticated LDAP user with write access to the aci attribute to silently corrupt heap memory in the directory server process by submitting a malformed Access Control Instruction string. The __aclp__normalize_acltxt() function in aclparse.c performs pointer arithmetic on the keyword portion of an ACI string without validating minimum remaining buffer length after whitespace stripping, resulting in a 1-byte out-of-bounds write followed by out-of-bounds reads (CWE-787). No public exploit or CISA KEV listing has been identified at time of analysis; an upstream fix is available via GitHub PR #7542 but a released patched version has not been independently confirmed.

Technical ContextAI

389 Directory Server is the open-source upstream project underlying Red Hat Directory Server (RHDS), an LDAP-compliant directory service deployed across RHEL 6 through 10 and RHDS versions 11, 12, and 13. Access Control Instructions (ACIs) in LDAP define fine-grained read/write/search permissions on directory entries; they are stored as string-valued attributes and parsed server-side when entries are modified. The vulnerable code path is in ldap/servers/plugins/acl/aclparse.c within __aclp__normalize_acltxt(), which normalizes ACI keyword text. After stripping leading whitespace, the function performs character-level pointer arithmetic (accessing *(s+1) and *(s+2)) without first confirming the buffer has at least three remaining bytes. For a malformed ACI with a keyword of zero, one, or two characters after stripping, this produces a 1-byte out-of-bounds write and subsequent reads into adjacent heap memory. The GitHub PR #7542 resolves this by inserting the guard if (s NULL || *s '\0' || *(s + 1) '\0' || *(s + 2) '\0') { goto error; } before the unsafe pointer dereferences, and also corrects a missing NULL check on a aclName >= s comparison.

RemediationAI

The upstream fix is available at https://github.com/389ds/389-ds-base/pull/7542 and adds ACI keyword length validation in __aclp__normalize_acltxt() to prevent out-of-bounds access; however, a released patched version of 389-ds-base or Red Hat Directory Server has not been independently confirmed, so administrators should monitor https://access.redhat.com/security/cve/CVE-2026-12528 for an official errata and apply it as soon as it is published. As an immediate compensating control, audit and restrict which LDAP users or roles hold write access to the aci attribute - this directly eliminates the exploit prerequisite and has no functional impact on end users who do not require ACI management. Additionally, enabling LDAP audit logging to capture all modify operations targeting aci attributes provides detection capability for exploitation attempts. Restricting aci write access may require updating delegation configurations and should be tested in a non-production environment first to avoid unintentionally locking out directory administrators.

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Same weakness CWE-787 – Out-of-bounds Write

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Same technique Buffer Overflow

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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-2026-12528 vulnerability details – vuln.today
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