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.
References10
- access.redhat.com/errata/RHSA-2026:64771
- access.redhat.com/errata/RHSA-2026:64776
- access.redhat.com/errata/RHSA-2026:64778
- access.redhat.com/errata/RHSA-2026:64779
- access.redhat.com/errata/RHSA-2026:64780
- access.redhat.com/errata/RHSA-2026:64781
- access.redhat.com/errata/RHSA-2026:64783
- access.redhat.com/errata/RHSA-2026:64784
- access.redhat.com/errata/RHSA-2026:64785
- access.redhat.com/errata/RHSA-2026:64789
Metrics
- CVSS 3.1
-
7.5
HIGH
Score source: CNA
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H - EPSS — exploit probability
- 1% percentile: 58 · as of 3 November 2026
- CWE
- CWE-191
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