CVE-2025-55159: slab allows out-of-bounds access in `get_disjoint_mut` due to incorrect bounds check

Severity: medium (CVSS 5.1 v4.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-08-11 · updated 2026-06-17
Weakness: CWE-119

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 products

tokio-rs slab: from 0.4.10, < 0.4.11

References

https://github.com/tokio-rs/slab/commit/2d65c514bc964b192bab212ddf3c1fcea4ae96b8
https://github.com/tokio-rs/slab/pull/152
https://github.com/tokio-rs/slab/security/advisories/GHSA-qx2v-8332-m4fv

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