CVE-2026-18453: NULL Pointer Dereference in Red Hat Red Hat Enterprise Linux 7 Extended Lifecycle Support
A flaw was found in 389 Directory Server. A missing NULL pointer check in the paged results handling of op_shared_search allows an unauthenticated remote attacker to crash the LDAP server by sending a crafted sequence of search requests using the USE_ONE_BACKEND control, resulting in denial of service.
AI Analysis
Technical Summary
This vulnerability in 389 Directory Server (Red Hat Directory Server 11) involves a missing NULL pointer check in the paged results handling of the op_shared_search operation. An unauthenticated remote attacker can exploit this by sending a crafted sequence of search requests using the USE_ONE_BACKEND control, causing the LDAP server process to crash. The crash leads to denial of service by stopping directory lookups and authentication services dependent on the LDAP server until it is restarted. The issue does not affect confidentiality or integrity of directory data. Disabling anonymous LDAP access removes the unauthenticated attack vector, but authenticated clients can still trigger the crash. Exposure to trusted networks reduces attack surface but does not eliminate the impact if the service is reachable. Red Hat has not identified a practical mitigation other than updating the affected package when a fix is released.
Potential Impact
The vulnerability allows an unauthenticated remote attacker to cause a denial of service by crashing the LDAP server process. This disrupts directory lookups and authentication services relying on the LDAP server until the process is restarted. There is no confidentiality or integrity impact as the flaw only causes a crash without data leakage or modification. The attack is easy to repeat and can be triggered by any client able to send search requests to the LDAP service. Disabling anonymous access reduces risk but does not fully mitigate the issue for authenticated clients. Restricting LDAP access to trusted networks reduces exposure but does not eliminate the risk if the service is reachable.
Mitigation Recommendations
Red Hat has not identified any practical mitigation for this issue other than updating the affected package once a fix is available. Disabling anonymous LDAP access removes the unauthenticated attack vector but does not prevent authenticated clients from triggering the crash. Restricting LDAP access to trusted networks reduces the attack surface but does not eliminate the risk. Users should monitor Red Hat advisories for the release of an official fix and apply it promptly.
CVE-2026-18453: NULL Pointer Dereference in Red Hat Red Hat Enterprise Linux 7 Extended Lifecycle Support
Description
A flaw was found in 389 Directory Server. A missing NULL pointer check in the paged results handling of op_shared_search allows an unauthenticated remote attacker to crash the LDAP server by sending a crafted sequence of search requests using the USE_ONE_BACKEND control, resulting in denial of service.
CVSS v3.1
Score 7.5high
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability in 389 Directory Server (Red Hat Directory Server 11) involves a missing NULL pointer check in the paged results handling of the op_shared_search operation. An unauthenticated remote attacker can exploit this by sending a crafted sequence of search requests using the USE_ONE_BACKEND control, causing the LDAP server process to crash. The crash leads to denial of service by stopping directory lookups and authentication services dependent on the LDAP server until it is restarted. The issue does not affect confidentiality or integrity of directory data. Disabling anonymous LDAP access removes the unauthenticated attack vector, but authenticated clients can still trigger the crash. Exposure to trusted networks reduces attack surface but does not eliminate the impact if the service is reachable. Red Hat has not identified a practical mitigation other than updating the affected package when a fix is released.
Potential Impact
The vulnerability allows an unauthenticated remote attacker to cause a denial of service by crashing the LDAP server process. This disrupts directory lookups and authentication services relying on the LDAP server until the process is restarted. There is no confidentiality or integrity impact as the flaw only causes a crash without data leakage or modification. The attack is easy to repeat and can be triggered by any client able to send search requests to the LDAP service. Disabling anonymous access reduces risk but does not fully mitigate the issue for authenticated clients. Restricting LDAP access to trusted networks reduces exposure but does not eliminate the risk if the service is reachable.
Mitigation Recommendations
Red Hat has not identified any practical mitigation for this issue other than updating the affected package once a fix is available. Disabling anonymous LDAP access removes the unauthenticated attack vector but does not prevent authenticated clients from triggering the crash. Restricting LDAP access to trusted networks reduces the attack surface but does not eliminate the risk. Users should monitor Red Hat advisories for the release of an official fix and apply it promptly.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- redhat
- Date Reserved
- 2026-07-31T06:49:45.234Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
- Vendor Advisory Urls
- [{"url":"https://access.redhat.com/security/cve/CVE-2026-18453","vendor":"Red Hat"}]
Threat ID: 6a9ec8b6acd9273b49c4cf8c
Added to database: 09/07/2026, 14:22:46 UTC
Last enriched: 09/07/2026, 14:37:46 UTC
Last updated: 09/08/2026, 02:37:42 UTC
Views: 13
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