matrix-sdk-base: Denial of service due to custom `m.room.join_rules` events

{
  "id": "6ae4c5cb9652f712d1717a1d8fc414dedaa8f3da880550808bffcf7cc5379fe1",
  "url": "https://osv.dev/vulnerability/RUSTSEC-2025-0135",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "matrix-sdk-base: Denial of service due to custom `m.room.join_rules` events",
    "summary": "The matrix-sdk-base crate is unable to handle responses that include custom m.room.join_rules values due to a serialization bug. This can be exploited to cause a denial-of-service condition, if a user is invited to a room with non-standard join rules, the crate's sync process will stall, preventing further processing for all rooms.",
    "evidence": "osv:RUSTSEC-2025-0135",
    "products": [
      {
        "name": {
          "value": "matrix-sdk-base",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "0.16.0",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "RUSTSEC-2025-0135",
      "aliases": [
        "CVE-2025-66622",
        "GHSA-jj6p-3m75-g2p3",
        "RUSTSEC-2025-0135"
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "0.0.0-0"
                },
                {
                  "fixed": "0.16.0"
                }
              ]
            }
          ],
          "package": {
            "name": "matrix-sdk-base",
            "purl": "pkg:cargo/matrix-sdk-base",
            "ecosystem": "crates.io"
          },
          "database_specific": {
            "cvss": null,
            "source": "https://github.com/rustsec/advisory-db/blob/osv/crates/RUSTSEC-2025-0135.json",
            "categories": [
              "denial-of-service"
            ],
            "informational": null
          },
          "ecosystem_specific": {
            "affects": {
              "os": [],
              "arch": [],
              "functions": []
            },
            "affected_functions": null
          }
        }
      ],
      "modified": "2026-10-12T18:00:07.355162307Z",
      "provider": "osv",
      "references": [
        "https://crates.io/crates/matrix-sdk-base",
        "https://rustsec.org/advisories/RUSTSEC-2025-0135.html",
        "https://github.com/matrix-org/matrix-rust-sdk/pull/5924"
      ],
      "provider_metadata": {
        "license": "CC0-1.0"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2025-66622",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 306374,
  "published_at": "2025-12-08T12:00:00+00:00"
}