Aliasing violations in splice, mutable iteration and cursors

{
  "id": "9b5f51634ed009451ce7967c7b90afedb39cbb5fa4cb7116207b0d38a5fb36a6",
  "url": "https://osv.dev/vulnerability/RUSTSEC-2026-0408",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Aliasing violations in splice, mutable iteration and cursors",
    "summary": "Four code paths create a pointer whose permission is later revoked, then write through it. Miri reports each as undefined behaviour under both the Tree Borrows and Stacked Borrows aliasing models (CWE-758). All four are reachable from safe code with standard `Ord` types. 1. **Splice back-pointer.** `split_off`, `split_off_index` and `append` stored the first spliced node's `prev` pointer from a reference to the head, then wrote through that same reference, invalidating the stored pointer. A later `pop_first` or `pop_front` writes through it. This affects all four collections. 2. **`SkipMap::range_mut` back pointer.** With an `Included` or `Excluded` upper bound, the back pointer came from a shared reference. `next_back` hands out `&mut V` through it, and writing to that value is undefined behaviour. 3. **`IterMut::next_back` reads a yielded node.** In `SkipList` and `SkipMap`, `next_back` read the predecessor node even after the front end had yielded it as `&mut`. The read freezes the caller's reference, and the caller's next write through it is undefined behaviour. This affects `iter_mut`, `values_mut` and `range_mut` used from both ends. 4. **Cursor list pointer.** `lower_bound_mut` and `upper_bound_mut` on `OrderedSkipList` and `SkipSet` (`cursor` feature) took the cursor's list pointer, then searched through `&self`. A comparator with interior-mutable state, such as a `Cell` call counter, wrote to the list's memory through that shared borrow and invalidated the cursor's p",
    "evidence": "osv:RUSTSEC-2026-0408",
    "products": [
      {
        "name": {
          "value": "skiplist",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "1.3.0",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "low",
    "structured": {
      "id": "RUSTSEC-2026-0408",
      "aliases": [
        "GHSA-924w-mwc9-86m8",
        "RUSTSEC-2026-0408"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "0.0.0-0"
                },
                {
                  "fixed": "1.3.0"
                }
              ]
            }
          ],
          "package": {
            "name": "skiplist",
            "purl": "pkg:cargo/skiplist",
            "ecosystem": "crates.io"
          },
          "database_specific": {
            "cvss": "CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N",
            "source": "https://github.com/rustsec/advisory-db/blob/osv/crates/RUSTSEC-2026-0408.json",
            "categories": [
              "memory-corruption"
            ],
            "informational": "unsound"
          },
          "ecosystem_specific": {
            "affects": {
              "os": [],
              "arch": [],
              "functions": [
                "skiplist::ordered_skip_list::OrderedSkipList::append",
                "skiplist::ordered_skip_list::OrderedSkipList::lower_bound_mut",
                "skiplist::ordered_skip_list::OrderedSkipList::split_off",
                "skiplist::ordered_skip_list::OrderedSkipList::split_off_index",
                "skiplist::ordered_skip_list::OrderedSkipList::upper_bound_mut",
                "skiplist::skip_list::SkipList::append",
                "skiplist::skip_list::SkipList::iter_mut",
                "skiplist::skip_list::SkipList::range_mut",
                "skiplist::skip_list::SkipList::split_off",
                "skiplist::skip_map::SkipMap::append",
                "skiplist::skip_map::SkipMap::iter_mut",
                "skiplist::skip_map::SkipMap::range_mut",
                "skiplist::skip_map::SkipMap::split_off",
                "skiplist::skip_map::SkipMap::values_mut",
                "skiplist::skip_set::SkipSet::append",
                "skiplist::skip_set::SkipSet::lower_bound_mut",
                "skiplist::skip_set::SkipSet::split_off",
                "skiplist::skip_set::SkipSet::split_off_index",
                "skiplist::skip_set::SkipSet::upper_bound_mut"
              ]
            },
            "affected_functions": null
          }
        }
      ],
      "modified": "2026-10-26T14:00:05.788796703Z",
      "provider": "osv",
      "references": [
        "https://crates.io/crates/skiplist",
        "https://rustsec.org/advisories/RUSTSEC-2026-0408.html",
        "https://github.com/JP-Ellis/rust-skiplist/pull/407"
      ],
      "provider_metadata": {
        "license": "CC0-1.0"
      }
    },
    "related_cves": [],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 454200,
  "published_at": "2026-10-24T12:00:00+00:00"
}