Rust advisories / maxminddb
Vulnerability LowRUSTSEC-2025-0132 · maxminddb
RUSTSEC-2025-0132: `Reader::open_mmap` unsoundly marks unsafe memmap operation as safe
Short answerA security vulnerability in the maxminddb crate: `Reader::open_mmap` unsoundly marks unsafe memmap operation as safe. GitHub rates it Low. Fixed in 0.27.0: update to a fixed version.
| Crate | maxminddb |
|---|---|
| Type | Vulnerability (memory-corruption) |
| Affected versions | From 0.11.0 before 0.27.0. |
| Fixed in | 0.27.0 |
| Severity | Low (GitHub rating) |
| Published | 2025-11-28 |
| Last changed | 2025-12-02 |
| Also known as | GHSA-mj73-j457-8x9q |
| Affected functions | maxminddb::Reader::open, maxminddb::Reader::open_mmap |
What to do
- See which version you have:
cargo tree -i maxminddb(it also shows which of your dependencies pulls it in). - Update within your version requirement:
cargo update -p maxminddb. If the fix is a newer major or minor than your requirement allows, raise it in Cargo.toml (for examplemaxminddb = "0.27.0") or update the dependency that pulls it in. - Check again with
cargo audit, or paste your Cargo.lock into our Cargo.toml checker.
Details from the advisory
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.
References
- Package: crates.io/crates/maxminddb
- Advisory: rustsec.org/advisories/RUSTSEC-2025-0132.html
- Report: github.com/oschwald/maxminddb-rust/issues/86
- Web: github.com/oschwald/maxminddb-rust/commit/98f0e4fff9678c841ed33f3b8a46322f6163c32a
From the RustSec Advisory Database (CC0-1.0) via the OSV export, downloaded Oct 24, 2026. Severity score computed from the published CVSS vector.
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