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.

Timeline

1. Sep 7, 2026, 2:14 PM UTCCVE published
2. Sep 8, 2026, 4:40 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: total

3. Oct 8, 2026, 2:14 PM UTCRecord last updated

Affected versions

• redhat-ds:11

  Version range not reported

• redhat-ds:11

  Version range not reported

• redhat-ds:11

  Version range not reported

• redhat-ds:12

  Version range not reported

• redhat-ds:12

  Version range not reported

• 389-ds-base

  Version range not reported

• 389-ds-base

  Version range not reported

• 389-ds-base

  Version range not reported

• 389-ds:1.4

  Version range not reported

• 389-ds:1.4

  Version range not reported

• 389-ds:1.4

  Version range not reported

• 389-ds:1.4

  Version range not reported

• 389-ds:1.4

  Version range not reported

• 389-ds:1.4

  Version range not reported

• 389-ds:1.4

  Version range not reported

• 389-ds-base

  Version range not reported

• 389-ds-base

  Version range not reported

• 389-ds-base

  Version range not reported

• 389-ds-base

  Version range not reported

• dirsrv/dirsrv-container-rhel10

  Version range not reported

• redhat-ds:12/389-ds-base

  Version range not reported

• 389-ds-base

  Version range not reported

• 389-ds-base

  Version range not reported

References 19