Stalwart Mail Server has Out-of-Memory Denial of Service via Malformed Nested MIME Messages

{
  "id": "9e388a0588c0eef530743d507e07a7d95fa1dde480bd6317af3ec262efd1ec14",
  "url": "https://osv.dev/vulnerability/CVE-2026-26312",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Stalwart Mail Server has Out-of-Memory Denial of Service via Malformed Nested MIME Messages",
    "summary": "Stalwart is a mail and collaboration server. A denial-of-service vulnerability exists in Stalwart Mail Server versions 0.13.0 through 0.15.4 where accessing a specially crafted email containing malformed nested `message/rfc822` MIME parts via IMAP or JMAP causes excessive CPU and memory consumption, potentially leading to an out-of-memory condition and server crash. The malformed structure causes the `mail-parser` crate to produce cyclical references in its parsed representation, which Stalwart then follows indefinitely. Version 0.15.5 contains a patch.",
    "evidence": "osv:CVE-2026-26312",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-26312",
      "aliases": [
        "CVE-2026-26312",
        "GHSA-jm95-876q-c9gw"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/stalwartlabs/stalwart",
              "type": "GIT",
              "events": [
                {
                  "introduced": "e79a4c65c7411d34bd4262e9ce1d748001028c77"
                },
                {
                  "fixed": "9aecfc1dfd53a87c8918a6a98123c50af2001998"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0.13.0"
                      },
                      {
                        "fixed": "0.15.5"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "cpe": "cpe:2.3:a:stalw:stalwart:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0.13.0"
                      },
                      {
                        "fixed": "0.15.5"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v0.15.4",
            "v0.15.3",
            "v0.15.2",
            "v0.15.1",
            "v0.15.0",
            "v0.14.1",
            "v0.14.0",
            "v0.13.4",
            "v0.13.3",
            "v0.13.2",
            "v0.13.1",
            "v0.13.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-26312.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:45.928927414Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/26xxx/CVE-2026-26312.json",
        "https://github.com/stalwartlabs/stalwart/security/advisories/GHSA-jm95-876q-c9gw",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-26312"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-770"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/26xxx/CVE-2026-26312.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-26312",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 514191,
  "published_at": "2026-02-19T21:05:11.788+00:00"
}