CVE-2026-18663Network attack vectorHinoki check available

Pre-auth heap corruption via stale pblock pointer

Published Aug 12, 2026 · Updated Aug 12, 2026

Double-free in Red Hat 389-ds-base allows remote attackers to corrupt the ns-slapd heap through a critical Session Tracking control. get_ldapmessage_controls_ext() stores decoded controls in SLAPI_REQCONTROLS, frees them when rejecting that critical control, and leaves the pblock pointer for operation_done() to free again. One unauthenticated BIND request reaches the path; jemalloc on RHEL 10 and RHDS 13 absorbs the second free without a demonstrated crash, disclosure, or privilege escalation.

CVSS severity5.9
Medium
EPSS probability0.43%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Double-free in Red Hat 389-ds-base allows remote attackers to corrupt the ns-slapd heap through a critical Session Tracking control. get_ldapmessage_controls_ext() stores decoded controls in SLAPI_REQCONTROLS, frees them when rejecting that critical control, and leaves the pblock pointer for operation_done() to free again. One unauthenticated BIND request reaches the path; jemalloc on RHEL 10 and RHDS 13 absorbs the second free without a demonstrated crash, disclosure, or privilege escalation.

The record

CVE
CVE-2026-18663
Published
Aug 12, 2026
Updated
Aug 12, 2026
Vendor
389 Directory Server
Product
Red Hat Directory Server
Classifications
CWE-415
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 12, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 12, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected versions are unavailable in this record. Check the vendor advisory for version and patch details.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

389 Directory Server · Red Hat Directory ServerAffected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 10Affected versions are unavailable in this record.

Published CVSS scores

5.9Red HatCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-415Double Free

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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