CVE-2026-18663: 389-ds-base: 389-ds-base: pre-authentication double-free in get_ldapmessage_controls_ext() via critical session tracking control
- Is it exploited?
Not on CISA's list. CISA has not added it to the Known Exploited Vulnerabilities catalog as of . If CISA adds it, this page shows it as known exploited.
- How likely is exploitation in the next 30 days?
- 0.5%
EPSS score, percentile 43.5 of all scored records. A probability estimated by FIRST, not a report of exploitation.
- How severe?
- 5.9 Medium
CVSS v3.1 base score, given by the CNA
- What should I do?
CISA has set no required action, because the vulnerability is not in KEV.
The CVE record links no vendor advisory, patch or mitigation.
- Which versions are affected?
Source: CISA KEV 2026.10.29, as of ; FIRST EPSS, as of ; CVE List, as of . About the data.
What to do
Workaround (from the CVE record)
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.
Advisories and patches
The CVE record links no vendor advisory, patch or mitigation.
This summary is based on the CVE record as of . Check the vendor's advisory before you act: affected versions and fixes can change.
Affected products and versions
As listed in the CVE record.
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Versions not listed are: unaffected.
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Versions not listed are: affected.
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Versions not listed are: unaffected.
Source: CVE List, as of . About the data.
About this vulnerability
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 Sessio…
Summary: CVE record, as of .
- CISA has not added CVE-2026-18663 to its Known Exploited Vulnerabilities (KEV) catalog, as of 29 Oct 2026.
- The CVE record was published on 12 Aug 2026.
- The CVE record carries a CVSS v3.1 base score of 5.9 (Medium), given by its CNA.
- FIRST's EPSS model puts the probability of exploitation in the next 30 days at 0.5% (percentile 43.5), as of 29 Oct 2026. EPSS is a statistical estimate, not a report of exploitation.
- CISA's SSVC assessment in the CVE record: exploitation none, automatable no, technical impact partial.
- The credits in the CVE record name Anthropic (Claude) as finder.
Source: CISA KEV 2026.10.29, as of ; CVE List, as of ; FIRST EPSS, as of . About the data.
Description
389-ds-base: 389-ds-base: pre-authentication double-free in get_ldapmessage_controls_ext() via critical session tracking control
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.
Source: CVE List, as of . About the data.
Weakness
CWE-415
CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record.
Timeline
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References
2
Known exploited Red Hat vulnerabilities
- CVE-2015-3246: Red Hat Libuser Race Condition Vulnerability
- CVE-2015-5287: Red Hat Automatic Bug Reporting Tool Privilege Escalation Vulnerability
- CVE-2018-14667: Red Hat JBoss RichFaces Framework Expression Language Injection Vulnerability
- CVE-2021-3560: Red Hat Polkit Incorrect Authorization Vulnerability
- CVE-2021-4034: Red Hat Polkit Out-of-Bounds Read and Write Vulnerability