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CVE-2026-18355 (GCVE-0-2026-18355)

Vulnerability from cvelistv5 – Published: 2026-09-07 14:14 – Updated: 2026-09-08 16:54
VLAI
Title
389-ds-base: 389-ds-base: heap buffer overflow via sasl wrapped-record length lower-bound underflow in sasl_io_start_packet()
Summary
A 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.
Severity
7.5 (High)
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
SSVC
Exploitation: none Automatable: no Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-09-08 16:40 UTC
CWE
  • CWE-191 - Integer Underflow (Wrap or Wraparound)
Assigner
References
URL Tags
https://access.redhat.com/errata/RHSA-2026:64771 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:64776 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:64778 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:64779 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:64780 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:64781 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:64783 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:64784 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:64785 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:64789 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:64790 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:64791 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:64792 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:64793 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:64804 vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/security/cve/CVE-2026-18355 vdb-entryx_refsource_REDHAT
https://bugzilla.redhat.com/show_bug.cgi?id=2509186 issue-trackingx_refsource_REDHAT
Impacted products
Vendor Product Version CPE status
Red Hat Red Hat Directory Server 11.7 E4S for RHEL 8 Unaffected: 8080020260903102346.f969626e , < * (rpm)
    cpe:/a:redhat:directory_server_e4s:11.7::el8
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Red Hat Red Hat Directory Server 11.9 for RHEL 8 Unaffected: 8100020260904171440.37ed7c03 , < * (rpm)
    cpe:/a:redhat:directory_server:11.9::el8
Create a notification for this product.
Red Hat Red Hat Directory Server 12.2 E4S for RHEL 9 Unaffected: 9020020260903155914.1674d574 , < * (rpm)
    cpe:/a:redhat:directory_server_e4s:12.2::el9
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Red Hat Red Hat Directory Server 12.4 E4S for RHEL 9 Unaffected: 9040020260903102623.1674d574 , < * (rpm)
    cpe:/a:redhat:directory_server_e4s:12.4::el9
Create a notification for this product.
Red Hat Red Hat Enterprise Linux 10 Unaffected: 0:3.2.0-10.el10_2 , < * (rpm)
    cpe:/o:redhat:enterprise_linux:10.2
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Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support Unaffected: 0:3.0.6-21.el10_0 , < * (rpm)
    cpe:/o:redhat:enterprise_linux_eus:10.0
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Red Hat Red Hat Enterprise Linux 7 Extended Lifecycle Support Unaffected: 0:1.3.11.1-15.el7_9 , < * (rpm)
    cpe:/o:redhat:rhel_els:7
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Red Hat Red Hat Enterprise Linux 8 Unaffected: 8100020260904155442.25e700aa , < * (rpm)
    cpe:/a:redhat:enterprise_linux:8::appstream
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Red Hat Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support Unaffected: 8040020260901171549.96015a92 , < * (rpm)
    cpe:/a:redhat:rhel_aus:8.4::appstream
    cpe:/a:redhat:rhel_eus_long_life:8.4::appstream
Create a notification for this product.
Red Hat Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On Unaffected: 8040020260901171549.96015a92 , < * (rpm)
    cpe:/a:redhat:rhel_aus:8.4::appstream
    cpe:/a:redhat:rhel_eus_long_life:8.4::appstream
Create a notification for this product.
Red Hat Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support Unaffected: 8060020260901145727.824efc52 , < * (rpm)
    cpe:/a:redhat:rhel_aus:8.6::appstream
    cpe:/a:redhat:rhel_eus_long_life:8.6::appstream
Create a notification for this product.
Red Hat Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On Unaffected: 8060020260901145727.824efc52 , < * (rpm)
    cpe:/a:redhat:rhel_aus:8.6::appstream
    cpe:/a:redhat:rhel_eus_long_life:8.6::appstream
Create a notification for this product.
Red Hat Red Hat Enterprise Linux 8.8 Telecommunications Update Service Unaffected: 8080020260831180218.6dbb3803 , < * (rpm)
    cpe:/a:redhat:rhel_e4s:8.8::appstream
    cpe:/a:redhat:rhel_tus:8.8::appstream
Create a notification for this product.
Red Hat Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions Unaffected: 8080020260831180218.6dbb3803 , < * (rpm)
    cpe:/a:redhat:rhel_e4s:8.8::appstream
    cpe:/a:redhat:rhel_tus:8.8::appstream
Create a notification for this product.
Red Hat Red Hat Enterprise Linux 9 Unaffected: 0:2.8.0-10.el9_8 , < * (rpm)
    cpe:/a:redhat:enterprise_linux:9::appstream
    cpe:/a:redhat:enterprise_linux:9::crb
Create a notification for this product.
Red Hat Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions Unaffected: 0:2.2.4-22.el9_2 , < * (rpm)
    cpe:/a:redhat:rhel_e4s:9.2::appstream
Create a notification for this product.
Red Hat Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions Unaffected: 0:2.4.5-29.el9_4 , < * (rpm)
    cpe:/a:redhat:rhel_e4s:9.4::appstream
Create a notification for this product.
Red Hat Red Hat Enterprise Linux 9.6 Extended Update Support Unaffected: 0:2.6.1-24.el9_6 , < * (rpm)
    cpe:/a:redhat:rhel_eus:9.6::appstream
    cpe:/a:redhat:rhel_eus:9.6::crb
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Red Hat Red Hat Directory Server 12     cpe:/a:redhat:directory_server:12
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Red Hat Red Hat Directory Server 13     cpe:/a:redhat:directory_server:13
Create a notification for this product.
Red Hat Red Hat Enterprise Linux 6     cpe:/o:redhat:enterprise_linux:6
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Date Public
2026-09-07 09:00
Credits
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.
Show details on NVD website
To clipboard 

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    "dateReserved": "2026-07-30T07:37:32.170Z",
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    "redhat_vex": {
      "aggregate_severity": "Important",
      "current_release_date": "2026-09-08T07:56:50+00:00",
      "cve": "CVE-2026-18355",
      "id": "CVE-2026-18355",
      "initial_release_date": "2026-09-07T09:00:00+00:00",
      "product_status:fixed": "472",
      "product_status:known_affected": "1",
      "product_status:known_not_affected": "5",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "389-ds-base: 389-ds-base: heap buffer overflow via SASL wrapped-record length lower-bound underflow in sasl_io_start_packet()",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-18355.json",
      "version": "3"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.