{"id":"RUSTSEC-2026-0236","revision":"4152d81a04da4db7acc599be65a990ff","records":[{"revision":"4152d81a04da4db7acc599be65a990ff","observedAt":"2026-10-24T13:19:54.901+00:00","statement":{"source":"osv","id":"RUSTSEC-2026-0236","aliases":["GHSA-6976-qm5m-7mcj"],"title":"A `BigInt` division panics, and two neighbouring operations answer wrongly in silence","description":"`viperjs` is a JavaScript engine intended to run untrusted script inside a host application, so\nscript text is data rather than a trusted caller and a panic reachable from script is a denial of\nservice in the embedder's process.\n\nA divisor whose magnitude lands exactly on the engine's internal limb ceiling reaches an\nout-of-bounds index. On every released version up to and including 0.2.1:\n\n```js\nconst d = (1n << 33554399n) * 2n;\n1n / d;   // panic: index out of bounds\n```\n\nTwo further operations on the same value returned wrong results without raising anything, which\nis the more dangerous half for an embedder that acts on the answer:\n\n```js\nd % 7n;      // 0n  — the true remainder is 1n\nString(d);   // \"0\"\n```\n\n## Cause\n\nThe left-shift helper reserved one limb for the bits a shift may push past the top of the\nmagnitude, measured *that* width against the size ceiling, and then trimmed the reserved limb away\nagain — so a magnitude landing exactly on the ceiling was refused on account of room it does not\nkeep. The division treated that refusal as unreachable and discarded it with `unwrap_or_default`,\nleaving an empty divisor magnitude; the subsequent `divisor[n - 1]` is then an index of\n`usize::MAX`.\n\nThe crate is `#![forbid(unsafe_code)]`, so this is a panic and not memory unsafety.\n\n## Remediation\n\nUpgrade to 0.2.2, in which all three behaviours are fixed: both divisions now produce correct\nresults, and `String()` of a magnitude beyond what the engine can divide raises a `RangeError`\nrather than producing `\"0\"` — ECMA-262 §6.1.4 requires an implementation that imposes a limit to\nthrow rather than answer something else.\n\nThere is no workaround short of upgrading; the values are reachable from any script the embedder\nevaluates.\n\nReported by [@Zniece](https://github.com/Zniece).","state":0,"publishedAt":"2026-08-06T12:00:00+00:00","modifiedAt":"2026-10-12T18:00:14.3099742+00:00","affected":[{"ecosystem":"crates.io","name":"viperjs","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"0.0.0-0"},{"kind":"fixed","version":"0.2.2"}]}],"versions":[],"rawVersionEvidence":null}],"metrics":[{"system":"CVSS_V3","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":null,"severity":null}],"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"],"sourceUrl":"https://osv.dev/vulnerability/RUSTSEC-2026-0236","license":"OSV · upstream source license applies","key":"osv:RUSTSEC-2026-0236","identifiers":["RUSTSEC-2026-0236","GHSA-6976-qm5m-7mcj"]},"retained":false,"historicalAffected":[]}],"coverage":[]}