CVE-2025-55159
Fix: tokio-rs/slab@2d65c51CVE-2025-55159 is a Buffer Overflow vulnerability in slab. O3 Security confirms whether CVE-2025-55159 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
slab allows out-of-bounds access in `get_disjoint_mut` due to incorrect bounds check
Real-World Exposure
slabReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.
Description
slab is a pre-allocated storage for a uniform data type. In version 0.4.10, the get_disjoint_mut method incorrectly checked if indices were within the slab's capacity instead of its length, allowing access to uninitialized memory. This could lead to undefined behavior or potential crashes. This has been fixed in slab 0.4.11. A workaround for this issue involves to avoid using get_disjoint_mut with indices that might be beyond the slab's actual length.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | slab | ≥ 0.4.10&&< 0.4.11 | 0.4.11 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for slab. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update slab to 0.4.11 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-55159 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2025-55159 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2025-55159. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2025-55159 in your dependencies?
O3 detects CVE-2025-55159 across crates.io dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.