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389-ds-base — security advisory

Type: advisorySources: OSVAdvisory ID: DEBIAN-CVE-2026-18355

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.

Products
389-ds-base
Affected 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+dfsg1-1+deb13u1, 3.1.2+vendor1-1, 3.1.2+vendor1-2, 3.3.0-1, 3.3.0-2, 3.3.1-1, 3.3.1-3
Fixed versions
Not specified
CVEs
CVE-2026-18355
Confirmed fixed CVEs
Not specified
Updated in this feed
28 Oct 2026, 11:07 UTC · Revision 1

Source evidence

DEBIAN-CVE-2026-18355

core-osv · Original source

Published 7 Sept 2026, 15:17 UTC

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.

osv:DEBIAN-CVE-2026-18355

389-ds-base

Fixed versions: Not specified

389-ds-base

Fixed versions: Not specified

Complete source record
{
  "id": "485245ffdcffe2ba029a01961e7b54ad186eca3dd911c3ac8ed9d92ed403a29f",
  "url": "https://osv.dev/vulnerability/DEBIAN-CVE-2026-18355",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "DEBIAN-CVE-2026-18355",
    "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.",
    "evidence": "osv:DEBIAN-CVE-2026-18355",
    "products": [
      {
        "name": {
          "value": "389-ds-base",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "2.3.1+dfsg1-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "2.3.1+dfsg1-1+deb12u1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "2.3.4+dfsg1-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "2.3.4+dfsg1-1.1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "2.4.4+dfsg1-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "2.4.4+dfsg1-3",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "2.4.5+dfsg1-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "3.0.2+dfsg1-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "3.1.1+dfsg1-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "3.1.1+dfsg1-2",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "3.1.1+dfsg1-3",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "3.1.2+dfsg1-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "3.1.2+vendor1-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "3.1.2+vendor1-2",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "3.3.0-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "3.3.0-2",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "3.3.1-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "3.3.1-3",
            "evidence": "/affected/0/versions"
          }
        ]
      },
      {
        "name": {
          "value": "389-ds-base",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "3.1.2+dfsg1-1",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "3.1.2+dfsg1-1+deb13u1",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "3.1.2+vendor1-1",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "3.1.2+vendor1-2",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "3.3.0-1",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "3.3.0-2",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "3.3.1-1",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "3.3.1-3",
            "evidence": "/affected/1/versions"
          }
        ]
      }
    ],
    "severity": "high",
    "structured": {
      "id": "DEBIAN-CVE-2026-18355",
      "aliases": [
        "DEBIAN-CVE-2026-18355"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "389-ds-base",
            "purl": "pkg:deb/debian/389-ds-base?arch=source&distro=bookworm",
            "ecosystem": "Debian:12"
          },
          "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",
            "3.3.1-1",
            "3.3.1-3"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-18355.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "389-ds-base",
            "purl": "pkg:deb/debian/389-ds-base?arch=source&distro=trixie",
            "ecosystem": "Debian:13"
          },
          "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",
            "3.3.1-1",
            "3.3.1-3"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-18355.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        }
      ],
      "modified": "2026-10-09T09:47:24.559791021Z",
      "provider": "osv",
      "upstream": [
        "CVE-2026-18355"
      ],
      "references": [
        "https://security-tracker.debian.org/tracker/CVE-2026-18355"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2026-18355",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 111469,
  "published_at": "2026-09-07T15:17:30.867+00:00"
}