{"id":"UBUNTU-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":"2026-09-16T14:01:37.376410064Z","published":"2026-09-07T15:17:00Z","upstream":["CVE-2026-18355"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-18355"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-18355"},{"type":"REPORT","url":"https://bugzilla.redhat.com/show_bug.cgi?id=2509186"}],"affected":[{"package":{"name":"389-ds-base","ecosystem":"Ubuntu:Pro:16.04:LTS","purl":"pkg:deb/ubuntu/389-ds-base?arch=source&distro=esm-apps%2Fxenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.3.3.12-1build1","1.3.3.13-1","1.3.4.5-2","1.3.4.8-1","1.3.4.8-3","1.3.4.8-3ubuntu1","1.3.4.8-4","1.3.4.9-1","1.3.4.9-1ubuntu0.1~esm1"],"ecosystem_specific":{"binaries":[{"binary_name":"389-ds","binary_version":"1.3.4.9-1ubuntu0.1~esm1"},{"binary_name":"389-ds-base","binary_version":"1.3.4.9-1ubuntu0.1~esm1"},{"binary_version":"1.3.4.9-1ubuntu0.1~esm1","binary_name":"389-ds-base-libs"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-18355.json"}},{"package":{"name":"389-ds-base","ecosystem":"Ubuntu:Pro:18.04:LTS","purl":"pkg:deb/ubuntu/389-ds-base?arch=source&distro=esm-apps%2Fbionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.3.7.5-1","1.3.7.5-1build1","1.3.7.5-1build2","1.3.7.9-1","1.3.7.10-1","1.3.7.10-1ubuntu1","1.3.7.10-1ubuntu1+esm1"],"ecosystem_specific":{"binaries":[{"binary_version":"1.3.7.10-1ubuntu1+esm1","binary_name":"389-ds"},{"binary_name":"389-ds-base","binary_version":"1.3.7.10-1ubuntu1+esm1"},{"binary_name":"389-ds-base-libs","binary_version":"1.3.7.10-1ubuntu1+esm1"},{"binary_version":"1.3.7.10-1ubuntu1+esm1","binary_name":"python3-dirsrvtests"},{"binary_name":"python3-lib389","binary_version":"1.3.7.10-1ubuntu1+esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-18355.json"}},{"package":{"name":"389-ds-base","ecosystem":"Ubuntu:Pro:20.04:LTS","purl":"pkg:deb/ubuntu/389-ds-base?arch=source&distro=esm-apps%2Ffocal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.4.1.6-4","1.4.1.6-4build1","1.4.2.4-1","1.4.2.4-1build1","1.4.3.2-1","1.4.3.2-1build1","1.4.3.6-2","1.4.3.6-2ubuntu0.1~esm1"],"ecosystem_specific":{"binaries":[{"binary_name":"389-ds","binary_version":"1.4.3.6-2ubuntu0.1~esm1"},{"binary_version":"1.4.3.6-2ubuntu0.1~esm1","binary_name":"389-ds-base"},{"binary_name":"389-ds-base-libs","binary_version":"1.4.3.6-2ubuntu0.1~esm1"},{"binary_name":"cockpit-389-ds","binary_version":"1.4.3.6-2ubuntu0.1~esm1"},{"binary_version":"1.4.3.6-2ubuntu0.1~esm1","binary_name":"python3-lib389"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-18355.json"}},{"package":{"name":"389-ds-base","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/389-ds-base?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.4.4.11-2build1","1.4.4.11-2build2","1.4.4.17-1","2.0.11-2","2.0.14-1","2.0.15-1","2.0.15-1ubuntu2"],"ecosystem_specific":{"binaries":[{"binary_version":"2.0.15-1ubuntu2","binary_name":"389-ds"},{"binary_name":"389-ds-base","binary_version":"2.0.15-1ubuntu2"},{"binary_name":"389-ds-base-libs","binary_version":"2.0.15-1ubuntu2"},{"binary_name":"cockpit-389-ds","binary_version":"2.0.15-1ubuntu2"},{"binary_name":"python3-lib389","binary_version":"2.0.15-1ubuntu2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-18355.json"}},{"package":{"name":"389-ds-base","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/389-ds-base?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.3.4+dfsg1-1","2.4.4+dfsg1-1ubuntu1","2.4.4+dfsg1-1ubuntu4","2.4.4+dfsg1-3","2.4.5+dfsg1-1"],"ecosystem_specific":{"binaries":[{"binary_name":"389-ds","binary_version":"2.4.5+dfsg1-1"},{"binary_name":"389-ds-base","binary_version":"2.4.5+dfsg1-1"},{"binary_name":"389-ds-base-libs","binary_version":"2.4.5+dfsg1-1"},{"binary_name":"cockpit-389-ds","binary_version":"2.4.5+dfsg1-1"},{"binary_name":"python3-lib389","binary_version":"2.4.5+dfsg1-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-18355.json"}},{"package":{"name":"389-ds-base","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/389-ds-base?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.1.2+dfsg1-1","3.1.2+vendor1-2"],"ecosystem_specific":{"binaries":[{"binary_name":"389-ds","binary_version":"3.1.2+vendor1-2"},{"binary_name":"389-ds-base","binary_version":"3.1.2+vendor1-2"},{"binary_version":"3.1.2+vendor1-2","binary_name":"389-ds-base-libs"},{"binary_name":"cockpit-389-ds","binary_version":"3.1.2+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