{"id":"DEBIAN-CVE-2026-18355","details":"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 \u003e 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.","modified":"2026-09-09T08:47:31.084906398Z","published":"2026-09-07T15:17:30.867Z","upstream":["CVE-2026-18355"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-18355"}],"affected":[{"package":{"name":"389-ds-base","ecosystem":"Debian:12","purl":"pkg:deb/debian/389-ds-base?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.3.1+dfsg1-1","2.3.1+dfsg1-1+deb12u1","2.3.4+dfsg1-1","2.3.4+dfsg1-1.1","2.4.4+dfsg1-1","2.4.4+dfsg1-3","2.4.5+dfsg1-1","3.0.2+dfsg1-1","3.1.1+dfsg1-1","3.1.1+dfsg1-2","3.1.1+dfsg1-3","3.1.2+dfsg1-1","3.1.2+vendor1-1","3.1.2+vendor1-2","3.3.0-1","3.3.0-2"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-18355.json"}},{"package":{"name":"389-ds-base","ecosystem":"Debian:13","purl":"pkg:deb/debian/389-ds-base?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.1.2+dfsg1-1","3.1.2+dfsg1-1+deb13u1","3.1.2+vendor1-1","3.1.2+vendor1-2","3.3.0-1","3.3.0-2"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-18355.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}