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GHSA-g23h-7vf9-xc25

Mimalloc Can Allocate Memory with Bad Alignment

5.5 MediumFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
Low
Availability
None

What each source reports

GitHub Advisories Score used5.5

Mimalloc Can Allocate Memory with Bad Alignment

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.

Record
GHSA-g23h-7vf9-xc25
CVSS 4.0
5.5 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P
Updated
2026-11-02
OSV5.5

Mimalloc Can Allocate Memory with Bad Alignment

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.

Record
GHSA-g23h-7vf9-xc25
CVSS 4.0
5.5 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P
Updated
2026-11-02
OSVRUSTSEC-2022-0094No score

Mimalloc Can Allocate Memory with Bad Alignment

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.

Record
RUSTSEC-2022-0094
Updated
2026-11-02

Affected packages

Affected packages
PackageAffectedFixed
mimalloc
crates.io
before 0.1.39
0.1.39
mimalloc
crates.io
0.0.0-0 up to 0.1.39
0.1.39

History

History
RecordedChangedSources
first indexedGitHub Advisories, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

GHSA-g23h-7vf9-xc25 is a medium vulnerability (CVSS 5.5) in mimalloc, published November 23, 2022. No source lists public exploit code. Fixed in mimalloc 0.1.39.

References

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