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
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
Thin evidence
One scorer or none| CNA (redhat) | CVSS 3.1 | 5.9 |
|---|
- 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:HExploitation evidence
Disclosed: evidence found.
CVE published 12 Aug 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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
| Product | Affected | Fixed in |
|---|---|---|
Red Hatredhat/389-ds-basepkg:rpm/redhat/389-ds-baseOther threats | Affected
| Fixed in
|
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.