Remote DoS through unchecked `IdList` allocation in negentropy

{
  "id": "0f09ebb737daff17a44937ab70cd8af9f2ca6aab3d630c2a2247cab73f08169a",
  "url": "https://osv.dev/vulnerability/RUSTSEC-2026-0365",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Remote DoS through unchecked `IdList` allocation in negentropy",
    "summary": "## Summary The `negentropy` crate is vulnerable to denial-of-service through an unchecked, peer-controlled ID count in reconciliation messages. With the `std` feature enabled, which is the default configuration, a small malformed message can trigger an enormous memory allocation and terminate the application. ## Details When processing an `IdList` range, the reconciliation parser uses the peer-provided ID count to reserve memory before checking whether the message contains the corresponding IDs: ```rust let mut their_elems: HashSet = HashSet::with_capacity(num_ids as usize); ``` An attacker can declare an arbitrarily large count without supplying any IDs. The allocation occurs before the parser reaches the ID-reading loop, which would otherwise reject the truncated message. With Rust's default allocation-error behavior, a failed allocation aborts the process rather than unwinding. Consequently, `catch_unwind` cannot contain the failure. Both `reconcile` and `reconcile_with_ids` reach the vulnerable parser. The patched versions validate the count against the remaining message length before allocating: ```rust if num_ids > (query.len() / ID_SIZE) as u64 { return Err(Error::ParseEndsPrematurely); } ``` ## Impact An unauthenticated remote attacker can terminate an application that exposes reconciliation to untrusted peers without additional validation. For example, a Nostr relay that forwards `NEG-OPEN` or `NEG-MSG` reconciliation payloads to the vulnerable parser can be taken do",
    "evidence": "osv:RUSTSEC-2026-0365",
    "products": [
      {
        "name": {
          "value": "negentropy",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "0.4.4",
            "evidence": "/affected/0/ranges"
          },
          {
            "value": "0.5.2",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "RUSTSEC-2026-0365",
      "aliases": [
        "RUSTSEC-2026-0365"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "0.2.0"
                },
                {
                  "fixed": "0.4.4"
                },
                {
                  "introduced": "0.5.0"
                },
                {
                  "fixed": "0.5.2"
                }
              ]
            }
          ],
          "package": {
            "name": "negentropy",
            "purl": "pkg:cargo/negentropy",
            "ecosystem": "crates.io"
          },
          "database_specific": {
            "cvss": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "source": "https://github.com/rustsec/advisory-db/blob/osv/crates/RUSTSEC-2026-0365.json",
            "categories": [
              "denial-of-service"
            ],
            "informational": null
          },
          "ecosystem_specific": {
            "affects": {
              "os": [],
              "arch": [],
              "functions": []
            },
            "affected_functions": null
          }
        }
      ],
      "modified": "2026-10-16T23:30:02.383532013Z",
      "provider": "osv",
      "references": [
        "https://crates.io/crates/negentropy",
        "https://rustsec.org/advisories/RUSTSEC-2026-0365.html",
        "https://github.com/nostrdevkit/negentropy/pull/14",
        "https://github.com/nostrdevkit/negentropy/commit/40f7290cbc5755a5ba3190279fbc848a97866280",
        "https://github.com/nostrdevkit/negentropy/commit/894a32c0ab9f3efd750b3cf06caee27b3f9c3f12"
      ],
      "provider_metadata": {
        "license": "CC0-1.0"
      }
    },
    "related_cves": [],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 349389,
  "published_at": "2026-10-14T12:00:00+00:00"
}