389-ds-base: 389-ds-base: heap buffer overflow via sasl wrapped-record length lower-bound underflow in sasl_io_start_packet()

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-18355
StatePUBLISHED
Assignerredhat
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-07 15:17:30 UTC
Updated2026-09-08 08:17:10 UTC
DescriptionA heap buffer overflow flaw was found in the SASL I/O layer of 389 Directory Server (389-ds-base). In sasl_io_start_packet(), the wrapped-record length read from the wire is validated only against an upper bound. A small wire length (0, 1, or 2) produces an encrypted_buffer_count below the already-consumed encrypted_buffer_offset, causing an unsigned subtraction underflow in sasl_io_read_packet(). PR_Recv is then requested to read approximately 4 GiB into a 1024-byte heap buffer, resulting in a heap buffer overflow with attacker-controlled content. After a successful SASL bind with integrity protection (SSF > 0), a remote authenticated attacker can cause a denial of service or potentially achieve remote code execution. This flaw is distinct from CVE-2026-11774, whose fix only guards against upper-bound overflow.

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from [email protected]

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

Problem Types: CWE-191 | CWE-191 Integer Underflow (Wrap or Wraparound)

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary7.5HIGHCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNACVSS7.5HIGHCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
High
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Red Hat Red Hat Directory Server 11.7 E4S For RHEL 8 unaffected 8080020260903102346.f969626e * rpm Not specified
CNA Red Hat Red Hat Directory Server 11.9 For RHEL 8 unaffected 8100020260904171440.37ed7c03 * rpm Not specified
CNA Red Hat Red Hat Directory Server 12.2 E4S For RHEL 9 unaffected 9020020260903155914.1674d574 * rpm Not specified
CNA Red Hat Red Hat Directory Server 12.4 E4S For RHEL 9 unaffected 9040020260903102623.1674d574 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 10 unaffected 0:3.2.0-10.el10_2 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support unaffected 0:3.0.6-21.el10_0 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 7 Extended Lifecycle Support unaffected 0:1.3.11.1-15.el7_9 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8 unaffected 8100020260904155442.25e700aa * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support unaffected 8040020260901171549.96015a92 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On unaffected 8040020260901171549.96015a92 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support unaffected 8060020260901145727.824efc52 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On unaffected 8060020260901145727.824efc52 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8.8 Telecommunications Update Service unaffected 8080020260831180218.6dbb3803 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 8.8 Update Services For SAP Solutions unaffected 8080020260831180218.6dbb3803 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 9 unaffected 0:2.8.0-10.el9_8 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 9.2 Update Services For SAP Solutions unaffected 0:2.2.4-22.el9_2 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 9.4 Update Services For SAP Solutions unaffected 0:2.4.5-29.el9_4 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 9.6 Extended Update Support unaffected 0:2.6.1-24.el9_6 * rpm Not specified
CNA Red Hat Red Hat Directory Server 12 Not specified Not specified
CNA Red Hat Red Hat Directory Server 13 Not specified Not specified
CNA Red Hat Red Hat Enterprise Linux 6 Not specified Not specified

References

ReferenceSourceLinkTags
access.redhat.com/errata/RHSA-2026:64781 [email protected] access.redhat.com
access.redhat.com/errata/RHSA-2026:64778 [email protected] access.redhat.com
access.redhat.com/errata/RHSA-2026:64779 [email protected] access.redhat.com
access.redhat.com/errata/RHSA-2026:64780 [email protected] access.redhat.com
access.redhat.com/errata/RHSA-2026:64783 [email protected] access.redhat.com
access.redhat.com/errata/RHSA-2026:64776 [email protected] access.redhat.com
access.redhat.com/security/cve/CVE-2026-18355 [email protected] access.redhat.com
access.redhat.com/errata/RHSA-2026:64784 [email protected] access.redhat.com
access.redhat.com/errata/RHSA-2026:64793 [email protected] access.redhat.com
access.redhat.com/errata/RHSA-2026:64771 [email protected] access.redhat.com
access.redhat.com/errata/RHSA-2026:64792 [email protected] access.redhat.com
access.redhat.com/errata/RHSA-2026:64804 [email protected] access.redhat.com
access.redhat.com/errata/RHSA-2026:64785 [email protected] access.redhat.com
access.redhat.com/errata/RHSA-2026:64789 [email protected] access.redhat.com
access.redhat.com/errata/RHSA-2026:64791 [email protected] access.redhat.com
bugzilla.redhat.com/show_bug.cgi [email protected] bugzilla.redhat.com
access.redhat.com/errata/RHSA-2026:64790 [email protected] access.redhat.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Red Hat would like to thank Adam Korczynski (Ada Logics), Arthur Chan (Ada Logics), David Korczynski (Ada Logics), and Team (Anthropic) for reporting this issue. (en)

Additional Advisory Data

SourceTimeEvent
CNA2026-07-08T00:00:00.000ZReported to Red Hat.
CNA2026-09-07T09:00:00.000ZMade public.

Workarounds

CNA: Red Hat has investigated whether a possible mitigation exists for this issue, and has not been able to identify a practical example. Please update the affected package as soon as possible.

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