# CVE-2026-14940: 389 Directory Server heap overflow in DN normalization

Source: https://junglewise.ai/threats/cve-2026-14940-389-directory-server-heap-overflow-in-dn-normalization  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-07. Updated: 2026-07-07  
License: CC BY 4.0 with a link back

CVE-2026-14940 · Severity: medium · CVSS 5.3 · Published 2026-07-07

A security vulnerability has been identified in the 389 Directory Server, a widely used enterprise-grade directory service. An unauthenticated remote attacker can send a specially crafted request that causes the server to crash or behave unpredictably. This could lead to a denial of service, impacting the availability of authentication and directory services for the organization.

Technologies: [389 Directory Server Project Directory Server](https://junglewise.ai/threats/technologies/directory-server). Vendors: [389 Directory Server Project](https://junglewise.ai/threats/vendors/389-directory-server-project).

## Quick answers

**Is CVE-2026-14940 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-14940 being exploited in the wild.

**How severe is CVE-2026-14940?** Medium severity, with a CVSS score of 5.3, published 7 July 2026.

**Which products and versions are affected?** 389 Directory Server Project Directory Server 2.8.0-7.el9_8 and earlier.

**Is there a fix for CVE-2026-14940?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-14940 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-14940?** Check whether you run 389 Directory Server Project Directory Server at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A heap-based buffer overflow exists in the slapi_dn_normalize_ext() function within ldap/servers/slapd/dn.c of 389-ds-base. The vulnerability is triggered during the normalization of a Distinguished Name (DN) that contains legacy-quoted values encoding multivalued nested Relative Distinguished Names (RDNs). When sorting RDN attribute-value pairs, the server fails to properly finalize nested tracking, leading to stale pointers and an out-of-bounds write in rdn_av_swap(). An unauthenticated attacker can exploit this by sending an LDAP operation with a crafted base DN, potentially causing a crash (SIGSEGV) or heap corruption. The issue has been reproduced on RHEL 9.8.

## Affected products

- 389 Directory Server Project 389-ds-base 2.8.0-7.el9_8 and earlier
- Red Hat Red Hat Directory Server 11, 12, 13
- Red Hat Red Hat Enterprise Linux 7, 8, 9, 10

## Timeline

- 2026-07-07: disclosed: Vulnerability reported and published to NVD

## References

- [https://access.redhat.com/downloads/content/package-browser/](https://access.redhat.com/downloads/content/package-browser/)
- [https://access.redhat.com/security/cve/CVE-2026-14940](https://access.redhat.com/security/cve/CVE-2026-14940)
- [https://bugzilla.redhat.com/show_bug.cgi?id=2497697](https://bugzilla.redhat.com/show_bug.cgi?id=2497697)

## Related threats

- [389 Directory Server denial of service via unbounded LDAP controls](https://junglewise.ai/threats/cve-2026-9064-389-directory-server-denial-of-service-via-unbounded-ldap-controls)