Medium · CVSS 5.9CVE-2026-18663

389-ds-base: 389-ds-base: pre-authentication double-free in get_ldapmessage_controls_ext() via critical session tracking controlCVE-2026-18663

Answer in brief

CVE-2026-18663 records a Medium severity (CVSS 5.9) vulnerability in 389-ds-base: 389-ds-base: pre-authentication double-free in get_ldapmessage_controls_ext() via critical session tracking control. The current sources do not mark it as known exploited. The current feed maps Red Hat/389-ds-base (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Aug 12, 2026Updated Nov 5, 2026Source checked Nov 10, 2026First seen by HOL Aug 12, 2026Material review Nov 5, 2026

Upstream Advisory

Key facts

Risk: Medium · CVSS 5.9
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Not reported

Why this deserves its current priority

CVSS is 5.9. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Red Hat/389-ds-base (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Red Hat/389-ds-basegeneric	*	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Red Hat/389-ds-base.
Review the reported fix. Source-reported workaround: On builds that include upstream Issue 7389 (committed 2026-04-09, present in 389-ds-base-3.2 branch), administrators can add the Session Tracking control OID (1.3.6.1.4.1.21008.108.63.1) to the ds-ignored-control-criticality configuration attribute. This causes the server to ignore the criticality flag on this control, preventing the vulnerable rejection path from being reached. Additionally, network-level restriction of access to the LDAP port (389/636) to trusted clients reduces exposure.

Evidence timeline and material changes

Published upstream
Aug 12, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Nov 5, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 12, 2026

Sources and claim methodology

Upstream source description

A flaw was found in 389-ds-base. The get_ldapmessage_controls_ext() function frees the parsed controls array on the Session Tracking critical-control rejection path without clearing the SLAPI_REQCONTROLS pblock slot. Operation teardown then frees the same pointer again, causing a double-free. An unauthenticated remote attacker can trigger this with a single BIND request carrying a critical Session Tracking control, resulting in heap corruption and potential denial of service.

Quoted source text, attributed separately from HOL analysis.

Package

Affected range

Fixed version

Red Hat/389-ds-basegeneric

Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Red Hat/389-ds-base.

Review the reported fix. Source-reported workaround: On builds that include upstream Issue 7389 (committed 2026-04-09, present in 389-ds-base-3.2 branch), administrators can add the Session Tracking control OID (1.3.6.1.4.1.21008.108.63.1) to the ds-ignored-control-criticality configuration attribute. This causes the server to ignore the criticality flag on this control, preventing the vulnerable rejection path from being reached. Additionally, network-level restriction of access to the LDAP port (389/636) to trusted clients reduces exposure.

Sources and claim methodology

Upstream source description

Quoted source text, attributed separately from HOL analysis.