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.
References
Configurations
No configuration.
History
No history.
Information
Published : 2026-09-07 15:17
Updated : 2026-09-08 22:17
NVD link : CVE-2026-18355
Mitre link : CVE-2026-18355
CVE.ORG link : CVE-2026-18355
JSON object : View
Products Affected
No product.
CWE
CWE-191
Integer Underflow (Wrap or Wraparound)