rustsec-2026-0252
Vulnerability from osv_rustsec
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.
| URL | Type | |
|---|---|---|
{
"affected": [
{
"database_specific": {
"categories": [
"memory-corruption"
],
"cvss": null,
"informational": "unsound"
},
"ecosystem_specific": {
"affected_functions": null,
"affects": {
"arch": [],
"functions": [],
"os": []
}
},
"package": {
"ecosystem": "crates.io",
"name": "orx-split-vec",
"purl": "pkg:cargo/orx-split-vec"
},
"ranges": [
{
"events": [
{
"introduced": "0.0.0-0"
},
{
"fixed": "4.0.0"
}
],
"type": "SEMVER"
}
],
"versions": []
}
],
"aliases": [],
"database_specific": {
"license": "CC0-1.0"
},
"details": "`SplitVec::extend_from_slice` increments the logical length `self.len` before cloning the incoming elements into the reserved slots. If an element\u0027s `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.\n\nThis is reachable from safe Rust \u2014 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.\n\n## Impact\n\nA 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.\n\nConfirmed 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.\n\n## Fix\n\nFixed in `orx-split-vec` 4.0.0, which no longer commits the length before the elements are cloned.",
"id": "RUSTSEC-2026-0252",
"modified": "2026-08-11T10:40:01Z",
"published": "2026-08-11T12:00:00Z",
"references": [
{
"type": "PACKAGE",
"url": "https://crates.io/crates/orx-split-vec"
},
{
"type": "ADVISORY",
"url": "https://rustsec.org/advisories/RUSTSEC-2026-0252.html"
},
{
"type": "REPORT",
"url": "https://github.com/orxfun/orx-split-vec/issues/95"
}
],
"related": [],
"severity": [],
"summary": "Panic-safety unsoundness in `SplitVec::extend_from_slice` (uninitialized read)"
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.