# CVE-2026-9064: 389-ds-base: 389-ds-base: unbounded ldap controls count in get_ldapmessage_controls_ext() causes cpu and heap amplification (remote dos)

Status: published. Published: 2026-05-20. Updated: 2026-11-05.

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.

## Remediation

- 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. (source: CNA: redhat)
- fix: RHSA-2026:26453: Red Hat Enterprise Linux Server (v. 7 ELS), Red Hat Enterprise Linux Server Optional (v. 7 ELS)

RHSA-2026:26458: Red Hat Directory Server 11.9 for RHEL 8

RHSA-2026:26457: Red Hat Enterprise Linux AppStream EUS (v. 10.0), Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0)

RHSA-2026:26456: Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux CodeReady Linux Builder (v. 10)

RHSA-2026:26459: Red Hat Enterprise Linux AppStream (v. 8)

RHSA-2026:26463: Red Hat Enterprise Linux AppStream AUS (v.8.4), Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4)

RHSA-2026:26460: Red Hat Enterprise Linux AppStream AUS (v.8.6), Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6)

RHSA-2026:26454: Red Hat Enterprise Linux AppStream E4S (v.8.8), Red Hat Enterprise Linux AppStream TUS (v.8.8)

RHSA-2026:26452: Red Hat Enterprise Linux AppStream E4S (v.9.2)

RHSA-2026:26464: Red Hat Enterprise Linux AppStream E4S (v.9.4)

RHSA-2026:26465: Red Hat CodeReady Linux Builder EUS (v.9.6), Red Hat Enterprise Linux AppStream EUS (v.9.6)

RHSA-2026:26455: Red Hat Enterprise Linux AppStream (v. 9), Red Hat Enterprise Linux CodeReady Linux Builder (v. 9)

RHSA-2026:26461: Red Hat Directory Server 11.5 E4S for RHEL 8

RHSA-2026:26597: Red Hat Directory Server 11.7 E4S for RHEL 8

RHSA-2026:26639: Red Hat Directory Server 12.2 E4S for RHEL 9

RHSA-2026:26599: Red Hat Directory Server 12.4 E4S for RHEL 9

RHSA-2026:27125: Red Hat Directory Server 13.2 (source: ADP: redhat-SADP)
- 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. (source: ADP: redhat-SADP)

## Affected products and versions

-  /  (389-ds-base): 0 (affected). Source: CNA: redhat
- Red Hat / Red Hat Directory Server 11.5 E4S for RHEL 8 (redhat-ds:11): ≥ 8060020260609102432.0ca98e7e; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Directory Server 11.7 E4S for RHEL 8 (redhat-ds:11): ≥ 8080020260610130252.f969626e; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Directory Server 11.9 for RHEL 8 (redhat-ds:11): ≥ 8100020260601104139.37ed7c03; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Directory Server 12.2 E4S for RHEL 9 (redhat-ds:12): ≥ 9020020260615123354.1674d574; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Directory Server 12.4 E4S for RHEL 9 (redhat-ds:12): ≥ 9040020260611130021.1674d574; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 10 (389-ds-base): ≥ 0:3.2.0-7.el10_2; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 10.0 Extended Update Support (389-ds-base): ≥ 0:3.0.6-18.el10_0; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 7 Extended Lifecycle Support (389-ds-base): ≥ 0:1.3.11.1-12.el7_9; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8 (389-ds:1.4): ≥ 8100020260601102239.25e700aa; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support (389-ds:1.4): ≥ 8040020260609102422.96015a92; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On (389-ds:1.4): ≥ 8040020260609102422.96015a92; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support (389-ds:1.4): ≥ 8060020260609102416.824efc52; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On (389-ds:1.4): ≥ 8060020260609102416.824efc52; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8.8 Telecommunications Update Service (389-ds:1.4): ≥ 8080020260610125847.6dbb3803; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions (389-ds:1.4): ≥ 8080020260610125847.6dbb3803; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9 (389-ds-base): ≥ 0:2.8.0-7.el9_8; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions (389-ds-base): ≥ 0:2.2.4-18.el9_2; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions (389-ds-base): ≥ 0:2.4.5-25.el9_4; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9.6 Extended Update Support (389-ds-base): ≥ 0:2.6.1-21.el9_6; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Directory Server 13.2 (dirsrv/dirsrv-container-rhel10): ≥ 1781714123; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Directory Server 12 (redhat-ds:12/389-ds-base): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Directory Server 13 (389-ds-base): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 6 (389-ds-base): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Directory Server 11.5 E4S for RHEL 8 (redhat-ds:11): ≥ 8060020260609102432.0ca98e7e; < * (unaffected, rpm). Source: ADP: redhat-SADP
- Red Hat / Red Hat Directory Server 11.7 E4S for RHEL 8 (redhat-ds:11): ≥ 8080020260610130252.f969626e; < * (unaffected, rpm). Source: ADP: redhat-SADP
- Red Hat / Red Hat Directory Server 11.9 for RHEL 8 (redhat-ds:11): ≥ 8100020260601104139.37ed7c03; < * (unaffected, rpm). Source: ADP: redhat-SADP
- Red Hat / Red Hat Directory Server 12.2 E4S for RHEL 9 (redhat-ds:12): ≥ 9020020260615123354.1674d574; < * (unaffected, rpm). Source: ADP: redhat-SADP
- Red Hat / Red Hat Directory Server 12.4 E4S for RHEL 9 (redhat-ds:12): ≥ 9040020260611130021.1674d574; < * (unaffected, rpm). Source: ADP: redhat-SADP
- Red Hat / Red Hat Enterprise Linux 10 (389-ds-base): ≥ 0:3.2.0-7.el10_2; < * (unaffected, rpm). Source: ADP: redhat-SADP
- Red Hat / Red Hat Enterprise Linux 10.0 Extended Update Support (389-ds-base): ≥ 0:3.0.6-18.el10_0; < * (unaffected, rpm). Source: ADP: redhat-SADP
- Red Hat / Red Hat Enterprise Linux 7 Extended Lifecycle Support (389-ds-base): ≥ 0:1.3.11.1-12.el7_9; < * (unaffected, rpm). Source: ADP: redhat-SADP
- Red Hat / Red Hat Enterprise Linux 8 (389-ds:1.4): ≥ 8100020260601102239.25e700aa; < * (unaffected, rpm). Source: ADP: redhat-SADP
- Red Hat / Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support (389-ds:1.4): ≥ 8040020260609102422.96015a92; < * (unaffected, rpm). Source: ADP: redhat-SADP
- Red Hat / Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On (389-ds:1.4): ≥ 8040020260609102422.96015a92; < * (unaffected, rpm). Source: ADP: redhat-SADP
- Red Hat / Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support (389-ds:1.4): ≥ 8060020260609102416.824efc52; < * (unaffected, rpm). Source: ADP: redhat-SADP
- Red Hat / Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On (389-ds:1.4): ≥ 8060020260609102416.824efc52; < * (unaffected, rpm). Source: ADP: redhat-SADP
- Red Hat / Red Hat Enterprise Linux 8.8 Telecommunications Update Service (389-ds:1.4): ≥ 8080020260610125847.6dbb3803; < * (unaffected, rpm). Source: ADP: redhat-SADP
- Red Hat / Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions (389-ds:1.4): ≥ 8080020260610125847.6dbb3803; < * (unaffected, rpm). Source: ADP: redhat-SADP
- Red Hat / Red Hat Enterprise Linux 9 (389-ds-base): ≥ 0:2.8.0-7.el9_8; < * (unaffected, rpm). Source: ADP: redhat-SADP
- Red Hat / Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions (389-ds-base): ≥ 0:2.2.4-18.el9_2; < * (unaffected, rpm). Source: ADP: redhat-SADP
- Red Hat / Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions (389-ds-base): ≥ 0:2.4.5-25.el9_4; < * (unaffected, rpm). Source: ADP: redhat-SADP
- Red Hat / Red Hat Enterprise Linux 9.6 Extended Update Support (389-ds-base): ≥ 0:2.6.1-21.el9_6; < * (unaffected, rpm). Source: ADP: redhat-SADP
- Red Hat / Red Hat Directory Server 13.2 (dirsrv/dirsrv-container-rhel10): ≥ 1781714123; < * (unaffected, rpm). Source: ADP: redhat-SADP
- Red Hat / Red Hat Directory Server 12 (redhat-ds:12/389-ds-base): Version range not reported. Source: ADP: redhat-SADP
- Red Hat / Red Hat Directory Server 13 (389-ds-base): Version range not reported. Source: ADP: redhat-SADP
- Red Hat / Red Hat Enterprise Linux 6 (389-ds-base): Version range not reported. Source: ADP: redhat-SADP

## Severity and prioritization

- CVSS 3.1: 7.5 (high); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H; source: CNA: redhat

- CVSS 3.1: 7.5 (high); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H; source: ADP: redhat-SADP

- CISA KEV: No listing in collected sources

- EPSS: 0.81% as of 2026-11-04; percentile 57.18%

- SSVC: exploitation none; automatable yes; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-770

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://access.redhat.com/errata/RHSA-2026:26452 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:26453 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:26454 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:26455 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:26456 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:26457 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:26458 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:26459 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:26460 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:26461 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:26463 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:26464 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:26465 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:26597 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:26599 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:26639 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:27125 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/security/cve/CVE-2026-9064 (CNA: redhat; vdb-entry, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2480093 (CNA: redhat; issue-tracking, x_refsource_REDHAT)

- https://access.redhat.com/security/cve/CVE-2026-9064 (ADP: redhat-SADP; vdb-entry, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2480093 (ADP: redhat-SADP; issue-tracking, x_refsource_REDHAT)

- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-9064.json (ADP: redhat-SADP; x_sadp-csaf-vex)

- https://access.redhat.com/errata/RHSA-2026:26453 (ADP: redhat-SADP; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:26458 (ADP: redhat-SADP; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:26457 (ADP: redhat-SADP; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:26456 (ADP: redhat-SADP; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:26459 (ADP: redhat-SADP; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:26463 (ADP: redhat-SADP; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:26460 (ADP: redhat-SADP; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:26454 (ADP: redhat-SADP; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:26452 (ADP: redhat-SADP; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:26464 (ADP: redhat-SADP; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:26465 (ADP: redhat-SADP; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:26455 (ADP: redhat-SADP; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:26461 (ADP: redhat-SADP; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:26597 (ADP: redhat-SADP; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:26639 (ADP: redhat-SADP; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:26599 (ADP: redhat-SADP; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:27125 (ADP: redhat-SADP; vendor-advisory, x_refsource_REDHAT)

## Provenance

- CNA: redhat: https://www.cve.org/CVERecord?id=CVE-2026-9064; retrieved 2026-11-05; source updated 2026-11-05

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-9064; retrieved 2026-11-05; source updated Not reported

Revision: 31eb800ab7863fc0cb09ba204278ea045bcf6356bfba61b6220ffdeecaacb79e

Canonical: https://y2.dev/cve/CVE-2026-9064

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