CVE-2025-55159 — slab
Fix: tokio-rs/slab@2d65c51CVE-2025-55159 is a Buffer Overflow vulnerability in slab. A fix is available for slab — see the affected versions and patch details below.
slab allows out-of-bounds access in `get_disjoint_mut` due to incorrect bounds check
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2025-55159.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
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 | 0.4.11cargo update -p slab --precise 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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2025-55159 can be triaged on real exposure rather than presence alone.
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 Security finds CVE-2025-55159 across crates.io dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.