{"id":"GHSA-36hh-v3qg-5jq4","aliases":["RUSTSEC-2026-0176"],"url":"https://o3.security/vulnerability/GHSA-36hh-v3qg-5jq4","summary":"PyO3 has an Out-of-bounds Read in `nth` / `nth_back` for `PyList` and `PyTuple` iterators","details":"PyO3 0.24.0 added optimized implementations of `Iterator::nth` and `DoubleEndedIterator::nth_back` for the `BoundListIterator` and `BoundTupleIterator` types. These implementations computed the target index using unchecked `usize` addition (`index + n`) before bounds-checking against the sequence length, then read the element via `get_item_unchecked`.\n\nIn `nth` methods, a sufficiently large `n` (combined with a non-zero internal index) could cause the addition to overflow and wrap around, producing a small \"target index\" that passed the bounds check and enabling reads at the front of the `list` or `tuple` of elements previously yielded by the iterator.\n\nIn `nth_back` methods, a sufficiently large `n` could cause underflow in a similar fashion, however would instead allow reads of arbitrary memory past the end of the `list` or `tuple` storage.","published":"2026-06-12T19:32:47Z","modified":"2026-09-10T03:51:07.658803617Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"crates.io","name":"pyo3","fixedVersion":"0.29.0"}],"fix":{"url":"https://github.com/PyO3/pyo3/pull/6086","label":"PyO3/pyo3#6086"},"references":[{"type":"WEB","url":"https://github.com/PyO3/pyo3/pull/6086"},{"type":"PACKAGE","url":"https://github.com/PyO3/pyo3"},{"type":"WEB","url":"https://rustsec.org/advisories/RUSTSEC-2026-0176.html"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-09-10T03:51:07.658803617Z"}}