GHSA-mj73-j457-8x9q `Reader::open_mmap` unsoundly marks unsafe memmap operation as safe

Not scored Published

An attacker can cause undefined behavior or crashes by modifying a memory-mapped file, potentially leading to code execution or denial of service.

Exploited in the wild
Not known
Login needed
Not needed
Attackable
Not stated
Victim action needed
Not needed
Fix
Available

What is GHSA-mj73-j457-8x9q?

GHSA-mj73-j457-8x9q is a memory corruption vulnerability in maxminddb, published on 28 Nov 2025.

Official description

maxminddb prior to version 0.27 declared Reader::open_mmap as safe despite wrapping an inherently unsafe memmap2 operation with no extra step done to guarantee safety. This could have led to undefined behaviour if the file were to be modified on disk while the memory map was still active.

Which versions are affected by GHSA-mj73-j457-8x9q?

3 open source packages ship an affected version, including maxminddb.

PackageAffectedFixed in
maxminddb crates.ioFrom 0.11.00.27.0
maxminddb crates.ioFrom 0.11.00.27.0
maxminddb crates.ioFrom 0.11.00.27.0

How do I fix GHSA-mj73-j457-8x9q?

Upgrade maxminddb to 0.27.0 or later.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is GHSA-mj73-j457-8x9q being exploited?

There is no known exploitation of GHSA-mj73-j457-8x9q in the wild and no public exploit code.

Sources

Also known as RUSTSEC-2025-0132.

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