CVE-2026-11787: 389-ds-base: 389-ds-base: heap buffer over-read in ldap_utf8prev() via str2simple filter parsing
A flaw was found in 389 Directory Server. The ldaputf8prev() function reads bytes before the start of a buffer without bounds checking, causing a heap buffer over-read in string filter parsing that may influence internal filter processing behavior.
Other sources
The ldaputf8prev() function in 389 Directory Server unconditionally reads up to 6 bytes before a heap allocation because it lacks a lower-bound parameter. This API design flaw has existed since the Mozilla LDAP C SDK import and was symptomatically patched twice without fixing the root cause. Twenty call sites remain vulnerable to 1-6 byte heap over-reads.
Cannot be triggered via standard LDAP wire protocol (BER filters parsed separately), but internal callers processing attacker-influenced data (plugin configuration, ACI definitions, replication) are affected. ASan confirmed on aarch64; no crash on production binaries.
— Red Hat
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2026-11787?
The severity of CVE-2026-11787 is classified as medium with a CVSS score of 5.
How do I fix CVE-2026-11787?
To fix CVE-2026-11787, update the 389 Directory Server to the latest patched version provided by Red Hat.
What type of vulnerability is CVE-2026-11787?
CVE-2026-11787 is a heap buffer over-read vulnerability in the ldap_utf8prev() function of the 389 Directory Server.
What impact does CVE-2026-11787 have?
CVE-2026-11787 may influence internal filter processing behavior, potentially leading to unexpected results or behaviors in the application.
Which software is affected by CVE-2026-11787?
CVE-2026-11787 affects the Red Hat 389 Directory Server (389-ds-base).