vulnerability / NVI-00018570 / Revision 1
smallbitvec: Integer overflow in safe API leads to heap buffer overflow
GitHub lists this reviewed advisory for smallbitvec. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
7.3 high
GitHub source severity; exploitability and local consequence require separate evidence.
As of · GitHub Advisory Database
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
smallbitvec
source listed>= 1.0.1, <= 2.6.0
### Summary An integer overflow in the internal capacity calculation of `smallbitvec` can lead to an undersized heap allocation, resulting in a heap buffer overflow through safe APIs only. This allows memory corruption without requiring `unsafe` code from the caller. ### Details The issue originates from unchecked arithmetic in the internal helper function responsible for computing the required buffer size: ``` (cap + bits_per_storage() - 1) / bits_per_storage() ``` When `cap` is close to `usize::MAX`, the addition: ``` cap + bits_per_storage() - 1 ``` can overflow in release builds and wrap around due to Rust’s default wrapping semantics for integer overflow in optimized builds. As a result: - `buffer_len(cap)` may return a value significantly smaller than required. - The backing storage is allocated with insufficient size. - Internal metadata (logical length/capacity) reflects a much larger size than the actual allocation. Subsequent safe API calls (e.g., `set`, `push`, `reserve`) rely on this corrupted metadata and perform index computations that assume sufficient backing storage. These operations eventually reach unsafe internal code paths (e.g., pointer arithmetic and u
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. GitHub Advisory Database
A fixed release is not deployment evidence.
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04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
05 / Provenance
Sources you can inspect
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- GHSA-97wc-2hqc-cjgr ↗
GitHub Advisory Database · vendor advisory
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Public revision history
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- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.