Summary
PyO3 has an Out-of-bounds Read in nth / nth_back for PyList and PyTuple iterators
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.
In 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.
In 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.
Impact
A read operation accesses a memory location beyond the intended buffer boundary. Typical impact: sensitive data disclosure or crash.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
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Frequently Asked Questions
- What is GHSA-36HH-V3QG-5JQ4? GHSA-36HH-V3QG-5JQ4 is a high-severity out-of-bounds read vulnerability in pyo3 (rust), affecting versions < 0.29.0. It is fixed in 0.29.0. A read operation accesses a memory location beyond the intended buffer boundary.
- Which versions of pyo3 are affected by GHSA-36HH-V3QG-5JQ4? pyo3 (rust) versions < 0.29.0 is affected.
- Is there a fix for GHSA-36HH-V3QG-5JQ4? Yes. GHSA-36HH-V3QG-5JQ4 is fixed in 0.29.0. Upgrade to this version or later.
- Is GHSA-36HH-V3QG-5JQ4 exploitable, and should I be worried? Whether GHSA-36HH-V3QG-5JQ4 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether GHSA-36HH-V3QG-5JQ4 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix GHSA-36HH-V3QG-5JQ4? Upgrade
pyo3to 0.29.0 or later.