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VulnerabilityPublished Updated

CVE-2026-18663: Red Hat Directory Server 13 389-ds-base · Double Free

Affects Red Hat Directory Server 13 389-ds-baseSource CVE Database V5

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Not known to be exploited · CVSS 5.9 Medium : upgrade the Red Hat redhat/389-ds-base package to 4.0.0 when convenient.

Data as of 10 Nov 2026, 23:24 UTC

CVSS 3.1 base score
5.9Medium
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (redhat)CVSS 3.15.9
EPSS
0.5% chance of exploitation in 30 days – higher than 43% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 4.0.0
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 12 Aug 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 10 Nov 2026.

What to do

Upgrade the Red Hat redhat/389-ds-base package to 4.0.0.

Affected software

ProductAffectedFixed in
Red Hatredhat/389-ds-basepkg:rpm/redhat/389-ds-baseOther threatsAffected
  • <4.0.0 >=3.0.0
Fixed in
  • 4.0.0

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Administrators can mitigate the issue by adding the Session Tracking control OID (1.3.6.1.4.1.21008.108.63.1) to the ds-ignored-control-criticality configuration attribute to ignore the criticality flag and prevent the vulnerable code path. Additionally, restricting network access to LDAP ports (389/636) to trusted clients reduces exposure. These mitigations reduce the risk until an official fix is available.

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.

References

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