Out-of-bounds read in `Log2Cache::nlog2n()`, `nlog2n_difference()` and `plog2p()`

{
  "id": "927db6d03653616e1d5a6c5587452e10dfd76d2d78ba06e492e6ed42c6948272",
  "url": "https://osv.dev/vulnerability/RUSTSEC-2026-0411",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Out-of-bounds read in `Log2Cache::nlog2n()`, `nlog2n_difference()` and `plog2p()`",
    "summary": "`Log2Cache::new(n)` fills its three tables with entries for `0..=n`, but the three accessor methods index those tables with `get_unchecked` on a value the caller supplies. Nothing bounds the argument and nothing documents a bound, so any value above the `n` the cache was built with reads past the end of the vector. `CountType` is `u32`, so the read can land up to `u32::MAX` elements away, and `plog2p()` returns the value it read, disclosing whatever lies there. For example, `Log2Cache::new(4)` builds tables holding 5 entries (indices 0,1,2,3,4). Then `cache.nlog2n(60000)` reads index 60000, far outside the allocation. Under AddressSanitizer this faults with `SEGV`; Miri reports it as undefined behavior at `src/log2cache.rs:42`. `nlog2n_difference()` is off by one further: in the affected versions `new(n)` pushes `n` entries into that table rather than `n + 1`, so even `nlog2n_difference(n)` is out of bounds. This can be triggered through safe public APIs — `Log2Cache::new()` and any of `nlog2n()`, `nlog2n_difference()` and `plog2p()` — with no `unsafe` required from the caller.",
    "evidence": "osv:RUSTSEC-2026-0411",
    "products": [
      {
        "name": {
          "value": "dahl-salso",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "0.7.0",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "RUSTSEC-2026-0411",
      "aliases": [
        "RUSTSEC-2026-0411"
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "0.0.0-0"
                },
                {
                  "fixed": "0.7.0"
                }
              ]
            }
          ],
          "package": {
            "name": "dahl-salso",
            "purl": "pkg:cargo/dahl-salso",
            "ecosystem": "crates.io"
          },
          "database_specific": {
            "cvss": null,
            "source": "https://github.com/rustsec/advisory-db/blob/osv/crates/RUSTSEC-2026-0411.json",
            "categories": [
              "memory-corruption",
              "memory-exposure"
            ],
            "informational": "unsound"
          },
          "ecosystem_specific": {
            "affects": {
              "os": [],
              "arch": [],
              "functions": []
            },
            "affected_functions": null
          }
        }
      ],
      "modified": "2026-10-26T14:00:05.091904359Z",
      "provider": "osv",
      "references": [
        "https://crates.io/crates/dahl-salso",
        "https://rustsec.org/advisories/RUSTSEC-2026-0411.html",
        "https://github.com/dbdahl/rust-dahl-salso/issues/2"
      ],
      "provider_metadata": {
        "license": "CC0-1.0"
      }
    },
    "related_cves": [],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 454193,
  "published_at": "2026-10-22T12:00:00+00:00"
}