{"aliases":["GHSA-8p3x-q3q3-q3v5"],"categories":[],"crate":"libz-sys","cves":[],"cvss":0.0,"database_specific":{"severity":""},"date":"2026-10-28","deb_packages":[{"crate_name":"bat","deb_name":"bat","version":"0.26.1+ds-2"},{"crate_name":"cargo-c","deb_name":"cargo-c","version":"0.10.25-1"},{"crate_name":"cargo-outdated","deb_name":"cargo-outdated","version":"0.19.0-4"},{"crate_name":"debcargo","deb_name":"debcargo","version":"2.8.4-5"},{"crate_name":"drt-tools","deb_name":"drt-tools","version":"0.3.5-3+b2"},{"crate_name":"eza","deb_name":"eza","version":"0.23.5-5"},{"crate_name":"feluda","deb_name":"feluda","version":"1.17.0-2"},{"crate_name":"git-absorb","deb_name":"git-absorb","version":"0.9.0-2"},{"crate_name":"git-cinnabar","deb_name":"git-cinnabar","version":"0.7.3-2+b2"},{"crate_name":"grcov","deb_name":"grcov","version":"0.10.7-2"},{"crate_name":"libz-sys","deb_name":"librust-libz-sys-dev","version":"1.1.20-1+b2"},{"crate_name":"lsd","deb_name":"lsd","version":"1.2.0-5"},{"crate_name":"prr","deb_name":"prr","version":"0.21.0-2+b2"},{"crate_name":"ripasso-cursive","deb_name":"ripasso-cursive","version":"0.8.0-1+b7"},{"crate_name":"sequoia-git","deb_name":"sequoia-git","version":"0.6.0-2+b2"}],"description":"The build script of `libz-sys` version <= 1.1.30 prints the full environment\nof the build, including any secrets it contains, to its stdout when compiled\nwith `cc@1.6.0` or later on a Unix host. This affects any build that depends on\n`libz-sys`. Cargo saves build script stdout under `target/`, so the values end\nup in anything that stores or shares the `target/` directory, such as CI caches.\n\nThis is similar to the [Miri issue](https://blog.rust-lang.org/2026/09/21/github-actions-leaking-secrets-when-miri-output-is-cached/).\n\n## Details\n\nTo decide whether to link against a system zlib, the `libz-sys` build script\ncompiles a small test program with a compiler command from `cc` and logs it\nwith:\n\n```rust\nprintln!(\"running {:?}\", cmd);\n```\n\nOn Unix, `Debug` impl for `std::process::Command` prints every environment\nvariable explicitly set on the command. Before `cc@1.6.0`, its\n`Tool::to_command()` set only a few compiler-specific variables. Starting with\n`cc@1.6.0` (released 2026-10-03), `Tool::to_command()` clears the environment\nand sets every variable explicitly.\n\nCargo parses build script stdout for `cargo:` directives, and stores the full\noutput in the build directory. It also prints it with `-vv`.\n\nThe probe runs for a default `libz-sys` build, including when pkg-config finds\nzlib, unless one of these applies:\n\n* the target is Windows, Android, Haiku or OpenHarmony\n* static linking is requested via the `static` feature or `LIBZ_SYS_STATIC=1`\n* the `zlib-ng` features are enabled without `stock-zlib`\n\n## Mitigations\n\nFixed in `libz-sys@1.1.31`, which no longer logs the probe command.\n\nIf you cannot upgrade, here are some workarounds:\n\n* Build with `LIBZ_SYS_STATIC=1` or the `static` feature, which skips the probe.\n* Pin `cc` to a release before 1.6.0 (`cargo update cc --precise <version>`).\n\nNote that upgrading `libz-sys` does not remove values already written. If an\naffected build already ran with secrets in its environment, clear CI caches and\nstored artifacts containing its\n[target/build directory](https://doc.rust-lang.org/nightly/cargo/reference/build-cache.html#build-cache),\nand consider rotating those secrets.","id":"RUSTSEC-2026-0418","keywords":["build-script","environment","secrets"],"patched_versions":[">=1.1.31"],"source":"debian_rustsec","title":"libz-sys build script leaks environment variables in the build directory","url":"https://github.com/rust-lang/libz-sys/pull/280"}