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CVE-2026-18355— 389-ds-base: 389-ds-base: heap buffer overflow via sasl wrapped-record length lower-bound underflow in sasl_io_start_packet()

Quick assessment

Affected
Red Hat Red Hat Directory Server 11.7 E4S for RHEL 8
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

在 389 Directory Server（389-ds-base）的 SASL I/O 层中，发现了一个堆缓冲区溢出漏洞。 在 函数中，从网络读取的封装记录长度仅根据上限进行校验。当接收到极小的网络长度值（0、1 或 2）时，会导致 小于已消耗的 ，从而在 中引发无符号整数减法下溢。随后，系统会请求 将大约 4 GiB 的数据读取到一个仅 1024 字节的堆缓冲区中，导致堆缓冲区溢出，且溢出内容由攻击者控制。 在完成带有完整性保护（SSF > 0）的 SASL 绑定后，经过身份验证的远程攻击者可利用此缺陷造成服

CVSS 7.5 · High

Possible ATT&CK Techniques 1 AI

T1210 · Exploitation of Remote Services

Affected Version Matrix 8

VendorProduct Version RangeStatus
Red Hat Red Hat Directory Server 11 any affected
Red Hat Red Hat Directory Server 12 any affected
Red Hat Red Hat Directory Server 13 any unaffected
Red Hat Red Hat Enterprise Linux 10 any affected
Red Hat Red Hat Enterprise Linux 6 any unaffected
Red Hat Red Hat Enterprise Linux 7 any affected
Red Hat Red Hat Enterprise Linux 8 any affected
Red Hat Red Hat Enterprise Linux 9 any affected
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I. Basic Information for CVE-2026-18355

Vulnerability Information
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Vulnerability Title
389-ds-base: 389-ds-base: heap buffer overflow via sasl wrapped-record length lower-bound underflow in sasl_io_start_packet()
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
整数下溢(超界折返)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Red Hat Red Hat Directory Server 11.7 E4S for RHEL 8 8080020260903102346.f969626e ~ * cpe:/a:redhat:directory_server_e4s:11.7::el8
Red Hat Red Hat Directory Server 11.9 for RHEL 8 8100020260904171440.37ed7c03 ~ * cpe:/a:redhat:directory_server:11.9::el8
Red Hat Red Hat Directory Server 12.2 E4S for RHEL 9 9020020260903155914.1674d574 ~ * cpe:/a:redhat:directory_server_e4s:12.2::el9
Red Hat Red Hat Directory Server 12.4 E4S for RHEL 9 9040020260903102623.1674d574 ~ * cpe:/a:redhat:directory_server_e4s:12.4::el9
Red Hat Red Hat Enterprise Linux 10 0:3.2.0-10.el10_2 ~ * cpe:/o:redhat:enterprise_linux:10.2
Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support 0:3.0.6-21.el10_0 ~ * cpe:/o:redhat:enterprise_linux_eus:10.0
Red Hat Red Hat Enterprise Linux 7 Extended Lifecycle Support 0:1.3.11.1-15.el7_9 ~ * cpe:/o:redhat:rhel_els:7
Red Hat Red Hat Enterprise Linux 8 8100020260904155442.25e700aa ~ * cpe:/a:redhat:enterprise_linux:8::appstream
Red Hat Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support 8040020260901171549.96015a92 ~ * cpe:/a:redhat:rhel_aus:8.4::appstream
Red Hat Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On 8040020260901171549.96015a92 ~ * cpe:/a:redhat:rhel_aus:8.4::appstream
Red Hat Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support 8060020260901145727.824efc52 ~ * cpe:/a:redhat:rhel_aus:8.6::appstream
Red Hat Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On 8060020260901145727.824efc52 ~ * cpe:/a:redhat:rhel_aus:8.6::appstream
Red Hat Red Hat Enterprise Linux 8.8 Telecommunications Update Service 8080020260831180218.6dbb3803 ~ * cpe:/a:redhat:rhel_e4s:8.8::appstream
Red Hat Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions 8080020260831180218.6dbb3803 ~ * cpe:/a:redhat:rhel_e4s:8.8::appstream
Red Hat Red Hat Enterprise Linux 9 0:2.8.0-10.el9_8 ~ * cpe:/a:redhat:enterprise_linux:9::appstream
Red Hat Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions 0:2.2.4-22.el9_2 ~ * cpe:/a:redhat:rhel_e4s:9.2::appstream
Red Hat Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions 0:2.4.5-29.el9_4 ~ * cpe:/a:redhat:rhel_e4s:9.4::appstream
Red Hat Red Hat Enterprise Linux 9.6 Extended Update Support 0:2.6.1-24.el9_6 ~ * cpe:/a:redhat:rhel_eus:9.6::appstream
Red Hat Red Hat Directory Server 12 - cpe:/a:redhat:directory_server:12
Red Hat Red Hat Directory Server 13 - cpe:/a:redhat:directory_server:13
Red Hat Red Hat Enterprise Linux 6 - cpe:/o:redhat:enterprise_linux:6

II. Public POCs for CVE-2026-18355

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III. Intelligence Information for CVE-2026-18355

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Vendor Advisories for CVE-2026-18355 (2)

Other References for CVE-2026-18355 (15)

Same Patch Batch · Red Hat · 2026-09-07 · 10 CVEs total

CVE-2026-18922 9.8 CRITICAL 389-ds-base: 389-ds-base: sasl plain authentication allows privilege escalation to directo
CVE-2026-76578 9.8 CRITICAL Ipa: freeipa: freeipa: unauthenticated ldap client can obtain administrator credentials vi
CVE-2026-86404 8.8 HIGH Artemis-server: artemis-jms-client: artemis-core-client: undertow-core: wildfly-messaging-
CVE-2026-19843 8.4 HIGH 389-ds-base: 389-ds-base: command injection via unescaped ldap dn in cockpit 389 console l
CVE-2026-79678 8.1 HIGH Freeipa: idm: freeipa: idp-add eval() reachable before authorization check allows environm
CVE-2026-18453 7.5 HIGH 389-ds-base: 389-ds-base: pre-authentication null pointer dereference via paged results an
CVE-2026-76560 7.5 HIGH 389-ds-base: 389-ds: anonymous ldap client can defeat selfdn aci bind-rule checks via empt
CVE-2026-86332 6.5 MEDIUM Odh-dashboard: odh-dashboard: nim credential secret readable by any authenticated user
CVE-2026-86469 5.3 MEDIUM Glib2: toctou symlink race in `g_file_create_replace_destination` fallback path

IV. Related Vulnerabilities

Same product: Red Hat Directory Server 11.7 E4S for RHEL 8
Same vendor: Red Hat
Same weakness: CWE-191

V. Comments for CVE-2026-18355

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