CVE-2026-9064389-ds-base: 389-ds-base: unbounded ldap controls count in get_ldapmessage_controls_ext() causes cpu and heap amplification (remote dos)

Description

A flaw was found in 389-ds-base. The get_ldapmessage_controls_ext() function in the LDAP server does not enforce an upper bound on the number of controls per LDAP message. A remote, unauthenticated attacker can send a specially crafted LDAP request containing hundreds of thousands of minimal controls within the default maximum BER message size (2 MB), causing excessive CPU consumption and heap allocation on the server. Under concurrent exploitation, this leads to significant latency degradation, worker thread starvation, or out-of-memory termination, resulting in a denial of service.

Timeline

Scores

EPSS (exploitation in 30 days)

0.81% · top 42% of all CVEs (13 Nov 2026)

CISA SSVC

Exploitation: none · Automatable: yes · Technical impact: partial

The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.5.

Affected products

• 389-ds-base

  • affected 0

• Red Hat · Red Hat Directory Server 11.5 E4S for RHEL 8

  • unaffected 8060020260609102432.0ca98e7e – < *

• Red Hat · Red Hat Directory Server 11.7 E4S for RHEL 8

  • unaffected 8080020260610130252.f969626e – < *

• Red Hat · Red Hat Directory Server 11.9 for RHEL 8

  • unaffected 8100020260601104139.37ed7c03 – < *

• Red Hat · Red Hat Directory Server 12.2 E4S for RHEL 9

  • unaffected 9020020260615123354.1674d574 – < *

• Red Hat · Red Hat Directory Server 12.4 E4S for RHEL 9

  • unaffected 9040020260611130021.1674d574 – < *

• Red Hat · Red Hat Enterprise Linux 10

  • unaffected 0:3.2.0-7.el10_2 – < *

• Red Hat · Red Hat Enterprise Linux 10.0 Extended Update Support

  • unaffected 0:3.0.6-18.el10_0 – < *

• Red Hat · Red Hat Enterprise Linux 7 Extended Lifecycle Support

  • unaffected 0:1.3.11.1-12.el7_9 – < *

• Red Hat · Red Hat Enterprise Linux 8

  • unaffected 8100020260601102239.25e700aa – < *

• Red Hat · Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support

  • unaffected 8040020260609102422.96015a92 – < *

• Red Hat · Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On

  • unaffected 8040020260609102422.96015a92 – < *

• Red Hat · Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support

  • unaffected 8060020260609102416.824efc52 – < *

• Red Hat · Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On

  • unaffected 8060020260609102416.824efc52 – < *

• Red Hat · Red Hat Enterprise Linux 8.8 Telecommunications Update Service

  • unaffected 8080020260610125847.6dbb3803 – < *

• Red Hat · Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions

  • unaffected 8080020260610125847.6dbb3803 – < *

• Red Hat · Red Hat Enterprise Linux 9

  • unaffected 0:2.8.0-7.el9_8 – < *

• Red Hat · Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions

  • unaffected 0:2.2.4-18.el9_2 – < *

• Red Hat · Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions

  • unaffected 0:2.4.5-25.el9_4 – < *

• Red Hat · Red Hat Enterprise Linux 9.6 Extended Update Support

  • unaffected 0:2.6.1-21.el9_6 – < *

• Red Hat · Red Hat Directory Server 13.2

  • unaffected 1781714123 – < *

• Red Hat · Red Hat Directory Server 12

  All versions: affected

• Red Hat · Red Hat Directory Server 13

  All versions: affected

• Red Hat · Red Hat Enterprise Linux 6

  All versions: unknown

What to do

Workaround: Restrict network access to the LDAP port (389/tcp, 636/tcp) to trusted networks only using firewall rules or network ACLs. This prevents untrusted remote attackers from reaching the vulnerable code path. Optionally, lower the nsslapd-maxbersize configuration parameter to reduce the maximum BER message size accepted by the server. Note that this caps bytes, not the number of controls, and does not fully eliminate the amplification. Setting it too low may impact legitimate LDAP operations with large payloads.

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• EUVD EUVD-2026-31079 (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisories (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2026-9064](https://cveledger.app/badge/CVE-2026-9064.svg)](https://cveledger.app/cve/CVE-2026-9064)

Record last updated 5 Nov 2026, 00:03 UTC.