CVE-2026-12528

389-ds-base: 389-ds-base: heap-buffer-overflows in __aclp__normalize_acltxt()

Published Jun 17, 2026 CVSS 3.1 · 5.4 Medium EPSS < 1% KEV · Not listed

Description

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.

Analysis

Technical impact

A buffer overflow occurs when 389 Directory Server parses a malformed Access Control Instruction. The __aclp__normalize_acltxt() function does not verify the length of an ACI keyword after whitespace stripping, allowing a one-byte write beyond the allocated buffer and subsequent reads outside bounds. An authenticated user who can write the aci attribute can supply a crafted ACI value, resulting in corruption of heap memory within the directory server process.

Affected Systems

The vulnerability affects Red Hat Directory Server versions 11, 12, and 13 and all Red Hat Enterprise Linux releases from 6 to 10 that include the 389-ds-base package. The affected products are listed as Red Hat Directory Server 11-13 and RHEL 6-10, as identified by the CNA.

Risk and Exploitability

The CVSS score of 5.4 indicates medium severity. The EPSS score is below 1 %, suggesting low likelihood of widespread exploitation, and the vulnerability is not currently in the CISA KEV catalog. Attack requires an authenticated user with write access to the aci attribute; if write permissions are overly permissive, the flaw can be exploited without elevated privilege. Successful exploitation would corrupt the server’s heap memory and could lead to process instability.

Affected Products

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor	Product	Default status	Versions
Red Hat	Red Hat Directory Server 11	affected	—
Red Hat	Red Hat Directory Server 12	affected	—
Red Hat	Red Hat Directory Server 13	affected	—
Red Hat	Red Hat Enterprise Linux 10	affected	—
Red Hat	Red Hat Enterprise Linux 6	unknown	—
Red Hat	Red Hat Enterprise Linux 7	affected	—
Red Hat	Red Hat Enterprise Linux 8	affected	—
Red Hat	Red Hat Enterprise Linux 9	affected	—

Configuration 1 [-]

OR	cpe:2.3:a:redhat:directory_server:11.0:::::::*
	cpe:2.3:a:redhat:directory_server:12.0:::::::*
	cpe:2.3:a:redhat:directory_server:13.0:::::::*
	cpe:2.3:o:redhat:389_directory_server:-:::::::*
	cpe:2.3:o:redhat:enterprise_linux:7.0:::::::*
	cpe:2.3:o:redhat:enterprise_linux:8.0:::::::*
	cpe:2.3:o:redhat:enterprise_linux:9.0:::::::*
	cpe:2.3:o:redhat:enterprise_linux:10.0:::::::*

No data.

Vendor Product Versions

Redhat

Directory Server

Version	Status	Scheme	Platform
`—`	affected	—	—

Redhat

Enterprise Linux

Version	Status	Scheme	Platform
`—`	affected	—	—

Remediation

Vendor Workaround

Ensure that only highly privileged accounts (Directory Manager or explicitly delegated ACI administrators) have write access to the 'aci' attribute. Review existing ACIs for overly broad targetattr rules (especially negated rules like targetattr!="..." or wildcards like targetattr="*") that may inadvertently grant regular users write access to operational attributes including 'aci'. The 389 DS ACI linting tool (lib389) can help identify such misconfigurations.

OpenCVE Recommended Actions

Restrict write access to the aci attribute so that only the Directory Manager or explicitly delegated ACI administrators can modify it.
Review existing ACIs for overly broad targetattr rules, and correct any misconfigurations. The lib389 ACI linting tool can help identify such policies.
Apply any available vendor updates or patch for 389‑ds‑base as soon as they become available; if no patch exists, monitor Red Hat advisories and apply the workaround promptly.

Generated by OpenCVE AI on June 18, 2026 at 20:34 UTC.

Tracking

Advisories

No advisories available

Metrics

No CVSS v4.0

Attack Vector Network

Attack Complexity Low

Privileges Required Low

Scope Unchanged

Confidentiality Impact None

Integrity Impact Low

Availability Impact Low

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Exploit prediction score: < 1% (0.226% probability within 30 days)

Exploitation none

Automatable no

Technical Impact partial

References

Link	Providers
https://access.redhat.com/security/cve/CVE-2026-12528
https://bugzilla.redhat.com/show_bug.cgi?id=2489835
https://github.com/389ds/389-ds-base/pull/7542
https://nvd.nist.gov/vuln/detail/CVE-2026-12528
https://www.cve.org/CVERecord?id=CVE-2026-12528

History

Nov 6, 2026 6:15 PM First appearance in the feed. Affected versions updated. Affected vendors updated View changes

Type	Values Removed	Values Added
First Time appeared		Redhat rhel Els
CPEs	cpe:/o:redhat:enterprise_linux:10 cpe:/o:redhat:enterprise_linux:6 cpe:/o:redhat:enterprise_linux:7 cpe:/o:redhat:enterprise_linux:8 cpe:/o:redhat:enterprise_linux:9	cpe:/a:redhat:enterprise_linux:10 cpe:/a:redhat:enterprise_linux:8 cpe:/a:redhat:enterprise_linux:9 cpe:/o:redhat:rhel_els:6 cpe:/o:redhat:rhel_els:7
Vendors & Products		Redhat rhel Els

Jun 18, 2026 4:45 PM Added references. Scoring metrics updated View changes

Type	Values Removed	Values Added
References		https://nvd.nist.gov/vuln/detail/CVE-2026-12528 https://www.cve.org/CVERecord?id=CVE-2026-12528
Metrics	threat_severity `None`	threat_severity `Low`

Jun 18, 2026 4:45 AM Description updated. Title updated. First appearance in the feed. Weaknesses updated. Affected versions updated. Affected vendors updated. Added references. Scoring metrics updated View changes

Type	Values Removed	Values Added
Description		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.
Title		389-ds-base: 389-ds-base: heap-buffer-overflows in __aclp__normalize_acltxt()
First Time appeared		Redhat Redhat directory Server Redhat enterprise Linux
Weaknesses		CWE-787
CPEs		cpe:/a:redhat:directory_server:11 cpe:/a:redhat:directory_server:12 cpe:/a:redhat:directory_server:13 cpe:/o:redhat:enterprise_linux:10 cpe:/o:redhat:enterprise_linux:6 cpe:/o:redhat:enterprise_linux:7 cpe:/o:redhat:enterprise_linux:8 cpe:/o:redhat:enterprise_linux:9
Vendors & Products		Redhat Redhat directory Server Redhat enterprise Linux
References		https://access.redhat.com/security/cve/CVE-2026-12528 https://bugzilla.redhat.com/show_bug.cgi?id=2489835 https://github.com/389ds/389-ds-base/pull/7542
Metrics		cvssV3_1 `{'score': 5.4, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L'}` ssvc `{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}`