Integer Underflow Affecting 389-ds-base-libs package, versions <0:2.8.0-10.el9_8


Severity

Recommended
critical

Based on Red Hat Enterprise Linux security rating.

Threat Intelligence

EPSS
0.84% (56th percentile)

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  • Snyk IDSNYK-RHEL9-389DSBASELIBS-19714043
  • published13 Sept 2026
  • disclosed7 Sept 2026

Introduced: 7 Sep 2026

NewCVE-2026-18355  (opens in a new tab)
CWE-191  (opens in a new tab)

How to fix?

Upgrade RHEL:9 389-ds-base-libs to version 0:2.8.0-10.el9_8 or higher.
This issue was patched in RHSA-2026:64784.

NVD Description

Note: Versions mentioned in the description apply only to the upstream 389-ds-base-libs package and not the 389-ds-base-libs package as distributed by RHEL. See How to fix? for RHEL:9 relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1