Buffer overflow in Red Hat Directory Server 11
CVE-2026-12528
A flaw was found in 389 Directory Server in the __aclp__normalize_acltxt() function of aclparse.c. A malformed ACI (Access Control Instruction) string can trigger heap-buffer-overflow writes and reads during ACI parsing. The function fails to validate that the ACI keyword has sufficient length after whitespace stripping, leading to a 1-byte out-of-bounds write and subsequent out-of-bounds reads. An authenticated user with write access to the aci attribute could send a crafted ACI value to silently corrupt heap memory in the directory server process.
Vulnerability class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L.
EPSS exploit prediction
EPSS: 0.002 (12.0th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 12th percentile — 12.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: 0.000
Affected products
Weakness classification (CWE)
References
- access.redhat.com/security/cve/CVE-2026-12528 (vdb-entry, Vendor Advisory)
- bugzilla.redhat.com/show_bug.cgi (issue-tracking, Issue Tracking, Vendor Advisory)
- github.com/389ds/389-ds-base/pull/7542 (Patch)
Frequently asked questions
- What is CVE-2026-12528?
- CVE-2026-12528 is a medium-severity vulnerability in Red Hat Directory Server 11, classified under Out-of-bounds Write. CVSS score: 5.4/10. Published 2026-06-17.
- How severe is CVE-2026-12528?
- Medium severity. CVSS v3 base score is 5.4 out of 10.