# CVE-2026-11610: 389-ds-base: 389-ds-base: heap buffer overflow in sasl_io_recv() via padded sasl unbind

Status: published. Published: 2026-07-07. Updated: 2026-11-04.

A heap buffer overflow flaw was found in the SASL I/O layer of 389 Directory Server
(389-ds-base). After a successful SASL bind with integrity protection (SSF > 0),
an authenticated attacker can send a specially crafted oversized LDAP UNBIND packet
that is copied into a 512-byte heap receive buffer without a bounds check in
sasl_io_recv() in sasl_io.c. This allows up to approximately 2 megabytes of
attacker-controlled data to overflow the buffer, causing a denial of service (server
crash). In FreeIPA and Red Hat Identity Management deployments, any domain user with
a valid Kerberos ticket, any enrolled host, or any service account can trigger this
vulnerability over the network after authenticating via GSSAPI.
The vulnerable code path has existed since approximately 2013 (389-ds-base 1.3.2) and
was not addressed by the CVE-2025-14905 fix, which patched a separate heap overflow
in schema.c only.

## Remediation

- workaround: There is no complete workaround for this flaw.
Mitigations that reduce exposure:
1. Restrict network access to LDAP ports (389/636) to trusted networks only.
   Note: In FreeIPA/IdM deployments, enrolled clients require LDAP access and
   this may not be practical.
2. If DIGEST-MD5 is not required, disable it via nsslapd-allowed-sasl-mechanisms
   in cn=config. GSSAPI/Kerberos cannot be disabled in FreeIPA/IdM without breaking
   domain authentication.
3. Monitor for oversized LDAP UNBIND packets (standard UNBIND is 7 bytes; alert on
   UNBIND packets exceeding ~100 bytes).
4. Lowering nsslapd-maxbersize reduces maximum overflow size but does not eliminate
   the vulnerability. (source: CNA: redhat)

## Affected products and versions

- 389ds / 389-ds-base (389-ds-base): ≥ 1.3.2; ≤ 3.3.0 (affected, semver). Source: CNA: redhat
- Red Hat / Red Hat Directory Server 11.5 E4S for RHEL 8 (redhat-ds:11): ≥ 8060020260702180044.0ca98e7e; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Directory Server 11.7 E4S for RHEL 8 (redhat-ds:11): ≥ 8080020260702180836.f969626e; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Directory Server 11.9 for RHEL 8 (redhat-ds:11): ≥ 8100020260702145313.37ed7c03; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Directory Server 12.2 E4S for RHEL 9 (redhat-ds:12): ≥ 9020020260703060155.1674d574; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Directory Server 12.4 E4S for RHEL 9 (redhat-ds:12): ≥ 9040020260703055735.1674d574; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 10 (389-ds-base): ≥ 0:3.2.0-8.el10_2; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 10.0 Extended Update Support (389-ds-base): ≥ 0:3.0.6-19.el10_0; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 7 Extended Lifecycle Support (389-ds-base): ≥ 0:1.3.11.1-13.el7_9; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8 (389-ds:1.4): ≥ 8100020260626120929.25e700aa; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support (389-ds:1.4): ≥ 8040020260629123121.96015a92; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On (389-ds:1.4): ≥ 8040020260629123121.96015a92; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support (389-ds:1.4): ≥ 8060020260626130540.824efc52; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On (389-ds:1.4): ≥ 8060020260626130540.824efc52; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8.8 Telecommunications Update Service (389-ds:1.4): ≥ 8080020260630025241.6dbb3803; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions (389-ds:1.4): ≥ 8080020260630025241.6dbb3803; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9 (389-ds-base): ≥ 0:2.8.0-8.el9_8; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions (389-ds-base): ≥ 0:2.2.4-19.el9_2; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions (389-ds-base): ≥ 0:2.4.5-26.el9_4; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9.6 Extended Update Support (389-ds-base): ≥ 0:2.6.1-22.el9_6; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Directory Server 13.2 (dirsrv/dirsrv-container-rhel10): ≥ 1783452100; < * (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

## Severity and prioritization

- CVSS 3.1: 8.8 (high); CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H; source: CNA: redhat

- CVSS 3.1: 8.8 (high); CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H; source: NVD: secalert@redhat.com

- CISA KEV: No listing in collected sources

- EPSS: 0.49% as of 2026-11-04; percentile 42.01%

- SSVC: exploitation none; automatable no; technical impact total; source ADP: CISA-ADP

- Weaknesses: CWE-122

## Exploit evidence

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

## References

- https://access.redhat.com/errata/RHSA-2026:36195 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:36196 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:36197 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:36198 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:36200 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:36201 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:36202 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:36204 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:36205 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:36206 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:36208 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:36209 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:36585 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:36641 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:36660 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:36670 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:36671 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/security/cve/CVE-2026-11610 (CNA: redhat; vdb-entry, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2484414 (CNA: redhat; issue-tracking, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:36195 (secalert@redhat.com)

- https://access.redhat.com/errata/RHSA-2026:36196 (secalert@redhat.com)

- https://access.redhat.com/errata/RHSA-2026:36197 (secalert@redhat.com)

- https://access.redhat.com/errata/RHSA-2026:36198 (secalert@redhat.com)

- https://access.redhat.com/errata/RHSA-2026:36200 (secalert@redhat.com)

- https://access.redhat.com/errata/RHSA-2026:36201 (secalert@redhat.com)

- https://access.redhat.com/errata/RHSA-2026:36202 (secalert@redhat.com)

- https://access.redhat.com/errata/RHSA-2026:36204 (secalert@redhat.com)

- https://access.redhat.com/errata/RHSA-2026:36205 (secalert@redhat.com)

- https://access.redhat.com/errata/RHSA-2026:36206 (secalert@redhat.com)

- https://access.redhat.com/errata/RHSA-2026:36208 (secalert@redhat.com)

- https://access.redhat.com/errata/RHSA-2026:36209 (secalert@redhat.com)

- https://access.redhat.com/errata/RHSA-2026:36585 (secalert@redhat.com)

- https://access.redhat.com/errata/RHSA-2026:36641 (secalert@redhat.com)

- https://access.redhat.com/errata/RHSA-2026:36660 (secalert@redhat.com)

- https://access.redhat.com/errata/RHSA-2026:36670 (secalert@redhat.com)

- https://access.redhat.com/errata/RHSA-2026:36671 (secalert@redhat.com)

- https://access.redhat.com/security/cve/CVE-2026-11610 (secalert@redhat.com)

- https://bugzilla.redhat.com/show_bug.cgi?id=2484414 (secalert@redhat.com)

## Provenance

- CNA: redhat: https://www.cve.org/CVERecord?id=CVE-2026-11610; retrieved 2026-11-04; source updated 2026-11-04

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-11610; retrieved 2026-11-05; source updated 2026-11-04

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-11610; retrieved 2026-11-04; source updated Not reported

Revision: 2abd6f9b735e36a564ef83fcc5e771a4dfbbb0273d3c65bf8dd542d505a05be9

Canonical: https://y2.dev/cve/CVE-2026-11610

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