RUSTSEC-2026-0252: Panic-safety unsoundness in `SplitVec::extend_from_slice` (uninitialized read)

What to do

1. See which version you have: cargo tree -i orx-split-vec (it also shows which of your dependencies pulls it in).
2. Update within your version requirement: cargo update -p orx-split-vec. If the fix is a newer major or minor than your requirement allows, raise it in Cargo.toml (for example orx-split-vec = "4.0.0") or update the dependency that pulls it in.
3. Check again with cargo audit, or paste your Cargo.lock into our Cargo.toml checker.

Details from the advisory

SplitVec::extend_from_slice increments the logical length self.len before cloning the incoming elements into the reserved slots. If an element's Clone panics mid-fill, unwinding leaves self.len counting slots that were never initialized. A later safe read (get, indexing, iter) then reads one of those uninitialized slots.

This is reachable from safe Rust , a read of uninitialized memory (CWE-908). It is not a double-free: SplitVec has no manual Drop and its elements live in a standard Vec, so the defect is a read, not a free.

Impact

A safe read after the panic returns a value built from uninitialized bytes. For a heap-owning element type such as String, the resulting value has garbage length/pointer fields.

Confirmed under Miri. AddressSanitizer stays silent for this class, since the uninitialized bytes are consumed as a non-dereferenced field rather than an invalid load or free.

Fix

Fixed in orx-split-vec 4.0.0, which no longer commits the length before the elements are cloned.

References

• Package: crates.io/crates/orx-split-vec
• Advisory: rustsec.org/advisories/RUSTSEC-2026-0252.html
• Report: github.com/orxfun/orx-split-vec/issues/95

From the RustSec Advisory Database (CC0-1.0) via the OSV export, downloaded Oct 24, 2026. Severity score computed from the published CVSS vector.