GHSA-g23h-7vf9-xc25 — mimalloc
GHSA-g23h-7vf9-xc25 is a security vulnerability in mimalloc. A fix is available for mimalloc — see the affected versions and patch details below.
Mimalloc Can Allocate Memory with Bad Alignment
Real-World Exposure
mimallocReal-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
This crate depended on a promise regarding alignments made by the author of the mimalloc allocator to avoid using aligned allocation functions where possible for performance reasons. Since then, the mimalloc allocator's logic changed, making it break this promise. This caused this crate to return memory with an incorrect alignment for some allocations, particularly those with large alignments. The flaw was fixed by always using the aligned allocation functions.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | mimalloc | all versions | 0.1.39cargo update -p mimalloc --precise 0.1.39 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for mimalloc, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update mimalloc to 0.1.39 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-g23h-7vf9-xc25 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 GHSA-g23h-7vf9-xc25 can be triaged on real exposure rather than presence alone.
Tailored to GHSA-g23h-7vf9-xc25. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-g23h-7vf9-xc25 in your dependencies?
O3 Security finds GHSA-g23h-7vf9-xc25 across crates.io dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.