{"id":"CVE-2026-18355","title":"A heap buffer overflow flaw was found in the SASL I/O layer of 389 Directory Server (389-ds-base)","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, …","severity":"high","cvss":7.5,"cvssVector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H","cwe":["CWE-191"],"vendor":"Red Hat","product":"redhat-ds:11","affected":["redhat-ds:11 (all versions)","redhat-ds:11 (all versions)","redhat-ds:12 (all versions)","redhat-ds:12 (all versions)","389-ds-base (all versions)","389-ds-base (all versions)","389-ds-base (all versions)","389-ds:1.4 (all versions)","389-ds:1.4 (all versions)","389-ds:1.4 (all versions)","389-ds:1.4 (all versions)","389-ds:1.4 (all versions)","389-ds:1.4 (all versions)","389-ds:1.4 (all versions)","389-ds-base (all versions)","389-ds-base (all versions)","389-ds-base (all versions)","389-ds-base (all versions)","dirsrv/dirsrv-container-rhel10 (all versions)","redhat-ds:12/389-ds-base (all versions)","389-ds-base","389-ds-base"],"published":"2026-09-07","updated":"2026-09-08","sourceUpdated":"2026-09-08T22:17:40.127","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-18355","references":[{"url":"https://access.redhat.com/errata/RHSA-2026:64771","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/errata/RHSA-2026:64776","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/errata/RHSA-2026:64778","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/errata/RHSA-2026:64779","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/errata/RHSA-2026:64780","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/errata/RHSA-2026:64781","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/errata/RHSA-2026:64783","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/errata/RHSA-2026:64784","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/errata/RHSA-2026:64785","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/errata/RHSA-2026:64789","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/errata/RHSA-2026:64790","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/errata/RHSA-2026:64791","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/errata/RHSA-2026:64792","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/errata/RHSA-2026:64793","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/errata/RHSA-2026:64804","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/errata/RHSA-2026:65119","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/security/cve/CVE-2026-18355","label":"secalert@redhat.com"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2509186","label":"secalert@redhat.com"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-18355.json"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-18355"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-18355"}],"tags":["nvd","cve.org","csaf","vex","red-hat"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-09-08T16:40:59.242163Z"},"epss":0.00837,"epssPercentile":0.55768,"ingestedAt":"2026-09-08T17:06:31.887Z","patched":["enterprise_linux_server_v_7_els","enterprise_linux_server_optional_v_7_els","directory_server_11_9_for_rhel 8","enterprise_linux_appstream_eus_v_10_0","enterprise_linux_appstream_v_10","enterprise_linux_appstream_v_8","enterprise_linux_appstream_aus_v_8_4","enterprise_linux_appstream_eus_extension_v_8_4","enterprise_linux_appstream_aus_v_8_6","enterprise_linux_appstream_eus_extension_v_8_6","enterprise_linux_appstream_e4s_v_8_8","enterprise_linux_appstream_tus_v_8_8","enterprise_linux_appstream_e4s_v_9_2","enterprise_linux_appstream_e4s_v_9_4","enterprise_linux_appstream_eus_v_9_6","enterprise_linux_appstream_v_9","directory_server_11_7_e4s_for_rhel 8","directory_server_12_2_e4s_for_rhel 9","directory_server_12_4_e4s_for_rhel 9","enterprise_linux_codeready_linux_builder_eus_v_10_0","enterprise_linux_codeready_linux_builder_v_10","codeready_linux_builder_eus_v_9_6","enterprise_linux_codeready_linux_builder_v_9","directory_server 13.2"],"slug":"CVE-2026-18355","body":"## Overview\n\nA 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **RHSA-2026:64771** · Red Hat · fixed in: Red Hat Enterprise Linux Server (v. 7 ELS), Red Hat Enterprise Linux Server Optional (v. 7 ELS) · released 2026-09-08 · [advisory](https://access.redhat.com/errata/RHSA-2026:64771)\n- **RHSA-2026:64793** · Red Hat · fixed in: Red Hat Directory Server 11.9 for RHEL 8 · released 2026-09-08 · [advisory](https://access.redhat.com/errata/RHSA-2026:64793)\n- **RHSA-2026:64804** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream EUS (v. 10.0), Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0) · released 2026-09-08 · [advisory](https://access.redhat.com/errata/RHSA-2026:64804)\n- **RHSA-2026:64785** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) · released 2026-09-08 · [advisory](https://access.redhat.com/errata/RHSA-2026:64785)\n- **RHSA-2026:64791** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream (v. 8) · released 2026-09-08 · [advisory](https://access.redhat.com/errata/RHSA-2026:64791)\n- **RHSA-2026:64789** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream AUS (v.8.4), Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4) · released 2026-09-08 · [advisory](https://access.redhat.com/errata/RHSA-2026:64789)\n- **RHSA-2026:64790** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream AUS (v.8.6), Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6) · released 2026-09-08 · [advisory](https://access.redhat.com/errata/RHSA-2026:64790)\n- **RHSA-2026:64776** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream E4S (v.8.8), Red Hat Enterprise Linux AppStream TUS (v.8.8) · released 2026-09-08 · [advisory](https://access.redhat.com/errata/RHSA-2026:64776)\n- **RHSA-2026:64778** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream E4S (v.9.2) · released 2026-09-08 · [advisory](https://access.redhat.com/errata/RHSA-2026:64778)\n- **RHSA-2026:64781** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream E4S (v.9.4) · released 2026-09-08 · [advisory](https://access.redhat.com/errata/RHSA-2026:64781)\n- **RHSA-2026:64783** · Red Hat · fixed in: Red Hat Enterprise Linux AppStream EUS (v.9.6), Red Hat CodeReady Linux Builder EUS (v.9.6) · released 2026-09-08 · [advisory](https://access.redhat.com/errata/RHSA-2026:64783)\n- **Red Hat VEX** · Important · affected: Red Hat Directory Server 12 · no fix planned: Red Hat Directory Server 12 · updated 2026-09-08 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-18355.json)","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":41.3,"likelihood":0.2,"exploitation":0,"ransomware":0},"changes":[]}