A `BigInt` division panics, and two neighbouring operations answer wrongly in silence

{
  "id": "bb9d58ee8bc4b0da404e85628c63e830e91f3883bc70336bf2665e902016b299",
  "url": "https://osv.dev/vulnerability/RUSTSEC-2026-0236",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "A `BigInt` division panics, and two neighbouring operations answer wrongly in silence",
    "summary": "`viperjs` is a JavaScript engine intended to run untrusted script inside a host application, so script text is data rather than a trusted caller and a panic reachable from script is a denial of service in the embedder's process. A divisor whose magnitude lands exactly on the engine's internal limb ceiling reaches an out-of-bounds index. On every released version up to and including 0.2.1: ```js const d = (1n << 33554399n) * 2n; 1n / d; // panic: index out of bounds ``` Two further operations on the same value returned wrong results without raising anything, which is the more dangerous half for an embedder that acts on the answer: ```js d % 7n; // 0n — the true remainder is 1n String(d); // \"0\" ``` ## Cause The left-shift helper reserved one limb for the bits a shift may push past the top of the magnitude, measured *that* width against the size ceiling, and then trimmed the reserved limb away again — so a magnitude landing exactly on the ceiling was refused on account of room it does not keep. The division treated that refusal as unreachable and discarded it with `unwrap_or_default`, leaving an empty divisor magnitude; the subsequent `divisor[n - 1]` is then an index of `usize::MAX`. The crate is `#![forbid(unsafe_code)]`, so this is a panic and not memory unsafety. ## Remediation Upgrade to 0.2.2, in which all three behaviours are fixed: both divisions now produce correct results, and `String()` of a magnitude beyond what the engine can divide raises a `RangeError` rather tha",
    "evidence": "osv:RUSTSEC-2026-0236",
    "products": [
      {
        "name": {
          "value": "viperjs",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "0.2.2",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "RUSTSEC-2026-0236",
      "aliases": [
        "GHSA-6976-qm5m-7mcj",
        "RUSTSEC-2026-0236"
      ],
      "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": "0.0.0-0"
                },
                {
                  "fixed": "0.2.2"
                }
              ]
            }
          ],
          "package": {
            "name": "viperjs",
            "purl": "pkg:cargo/viperjs",
            "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-2026-0236.json",
            "categories": [
              "denial-of-service"
            ],
            "informational": null
          },
          "ecosystem_specific": {
            "affects": {
              "os": [],
              "arch": [],
              "functions": []
            },
            "affected_functions": null
          }
        }
      ],
      "modified": "2026-10-12T18:00:14.309974197Z",
      "provider": "osv",
      "references": [
        "https://crates.io/crates/viperjs",
        "https://rustsec.org/advisories/RUSTSEC-2026-0236.html",
        "https://github.com/MerlijnW70/viperjs/commit/92988456c44fe7744c13cba1d891f127b8437f95",
        "https://github.com/MerlijnW70/viperjs/releases/tag/v0.2.2"
      ],
      "provider_metadata": {
        "license": "CC0-1.0"
      }
    },
    "related_cves": [],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 306459,
  "published_at": "2026-08-06T12:00:00+00:00"
}