Heap Buffer Overflow in 389 Directory Server by Red Hat
CVE-2026-18355

7.5HIGH

Key Information:

Vendor

Red Hat
Status
Red Hat Directory Server 11.7 E4s For Rhel 8
Red Hat Directory Server 11.9 For Rhel 8
Red Hat Directory Server 12.2 E4s For Rhel 9
Red Hat Directory Server 12.4 E4s For Rhel 9
Vendor
CVE Published:
7 September 2026

What is CVE-2026-18355?

A heap buffer overflow vulnerability exists within the SASL I/O layer of the 389 Directory Server. This flaw is exploited when the wrapped-record length read from the network is improperly validated, allowing an attacker to manipulate buffer lengths. Affected systems can face severe consequences, including denial of service and the risk of remote code execution. The issue arises specifically when an attacker successfully binds to the server with integrity protection enabled, facilitating malicious data input that could overflow a defined heap buffer. This condition enables unauthorized access and manipulation of memory, highlighting the importance of timely updates and patches.

Affected Version(s)

Red Hat Directory Server 11.7 E4S for RHEL 8 8080020260903102346.f969626e

Red Hat Directory Server 11.9 for RHEL 8 8100020260904171440.37ed7c03

Red Hat Directory Server 12.2 E4S for RHEL 9 9020020260903155914.1674d574

References

https://access.redhat.com/errata/RHSA-2026:64771
vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:64776
vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:64778
vendor-advisoryx_refsource_REDHAT

CVSS V3.1

Score:
7.5
Severity:
HIGH
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
High
Privileges Required:
Low
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Red Hat would like to thank Adam Korczynski (Ada Logics), Arthur Chan (Ada Logics), David Korczynski (Ada Logics), and Team (Anthropic) for reporting this issue.
.