cargo-unmaintained

Find unmaintained packages in Rust projects

cargo-unmaintained is similar to cargo-audit. However, cargo-unmaintained finds unmaintained packages automatically using heuristics, rather than rely on users to manually submit them to the RustSec Advisory Database.

cargo-unmaintained defines an unmaintained package X as one that satisfies one of 1 through 3 below:

1. X's repository is archived (see Notes below).

2. X is not a member of its named repository.

3. Both a and b below.

   a. X depends on a package Y whose latest version:

   • is incompatible with the version that X depends on
   • was released over a year ago (a configurable value)

   b. Either X has no associated repository, or its repository's last commit was over a year ago (a configurable value).

As of 2025-03-13, the RustSec Advisory Database contains 136 active advisories for unmaintained packages. Using the above conditions, cargo-unmaintained automatically identifies 101 (74%) of them. These results can be reproduced by running the rustsec_advisories example within this repository.

Notes

• To check whether packages' repositories have been archived, set the GITHUB_TOKEN_PATH environment variable to the path of a file containing a personal access token. If unset, this check will be skipped.

• The above conditions consider a "leaf" package (i.e., a package with no dependencies) unmaintained only if conditions 1 or 2 apply.

• The purpose of the "over a year ago" qualifications in condition 3 is to give package maintainers a chance to update their packages. That is, an incompatible upgrade to one of X's dependencies could require time-consuming changes to X. Without this check, cargo-unmaintained would produce many false positives.

• Of the 35 packages in the RustSec Advisory Database not identified by cargo-unmaintained:

  • 11 do not build
  • 3 are existent, unarchived leaves
  • 2 were updated within the past 365 days
  • 19 were not identified for other reasons

Output

cargo-unmaintained's output includes the number of days since a package's repository was last updated, along with the dependencies that cause the package to be considered unmaintained.

For example, the following is the output produced by running cargo-unmaintained on Cargo 0.74.0 on 2023-11-11:

Installation

cargo install cargo-unmaintained

Usage

Usage: cargo unmaintained [OPTIONS]

Options:
      --color <WHEN>    When to use color: always, auto, or never [default: auto]
      --fail-fast       Exit as soon as an unmaintained package is found
      --json            Output JSON (experimental)
      --max-age <DAYS>  Age in days that a repository's last commit must not exceed for the
                        repository to be considered current; 0 effectively disables this check,
                        though ages are still reported [default: 365]
      --no-cache        Do not cache data on disk for future runs
      --no-exit-code    Do not set exit status when unmaintained packages are found
      --no-warnings     Do not show warnings
  -p, --package <NAME>  Check only whether package NAME is unmaintained
      --purge           Remove all cached data from disk and exit
      --save-token      Read a personal access token from standard input and save it to
                        $HOME/.config/cargo-unmaintained/token.txt
      --tree            Show paths to unmaintained packages
      --verbose         Show information about what cargo-unmaintained is doing
  -h, --help            Print help
  -V, --version         Print version

The `GITHUB_TOKEN_PATH` environment variable can be set to the path of a file containing a personal
access token. If set, cargo-unmaintained will use this token to authenticate to GitHub and check
whether packages' repositories have been archived.

Alternatively, the `GITHUB_TOKEN` environment variable can be set to a personal access token.
However, use of `GITHUB_TOKEN_PATH` is recommended as it is less likely to leak the token.

If neither `GITHUB_TOKEN_PATH` nor `GITHUB_TOKEN` is set, but a file exists at
$HOME/.config/cargo-unmaintained/token.txt, cargo-unmaintained will use that file's contents as a
personal access token.

Unless --no-exit-code is passed, the exit status is 0 if no unmaintained packages were found and no
irrecoverable errors occurred, 1 if unmaintained packages were found, and 2 if an irrecoverable
error occurred.

Ignoring packages

If a workspace's Cargo.toml file includes a workspace.metadata.unmaintained.ignore array, all packages named therein will be ignored. Example:

[workspace.metadata.unmaintained]
ignore = ["matchers"]

Testing

Running just cargo test will not run the "continuous integration" or "externally influenced" tests. To run those additional tests, add --workspace, i.e.:

cargo test --workspace

Known problems

• If a package is renamed from X to Y, it is immediately considered unmaintained because the package's repository no longer contains a package named X. (#441)

• If a project relies on an old version of a package, cargo-unmaintained may fail to flag the package as unmaintained (i.e., may produce a false negative). The following is a sketch of how this can occur.

  • The project relies on version 1 of package X, which has no dependencies.
  • Version 2 of package X exists, and adds version 1 of package Y as a dependency.
  • Version 2 of package Y exists.

  Note that version 1 of package X appears maintained, but version 2 does not. Ignoring a few details, version 2 satisfies condition 3 above.

  cargo-unmaintained does not, in all cases, check whether the latest version of a package is used, as doing so would be cost prohibitive. A downside of this choice is that false negatives can result.

  Note that false positives should not arise in a corresponding way. Before flagging a package as unmaintained, cargo-unmaintained verifies that the package's latest version would be considered unmaintained as well.

Questions

• Yesterday, I got a warning about an unmaintained package. But, today, I don't. Why is that?

  Possibly, an intermediate dependency was updated. Suppose package X depends on Y, which depends on Z. And suppose Z is considered unmaintained. Then Z will generated warnings for both X and Y. If Y is updated to no longer depend upon Z, and X uses the new version of Y, then X will no longer receive warnings about Z.

Anti-goals

cargo-unmaintained is not meant to be a replacement for cargo-upgrade. cargo-unmaintained should not warn just because a package needs to be upgraded.

Semantic versioning policy

We reserve the right to change the following and to consider such changes non-breaking:

• what data is stored in the cache, as well as how that data is stored
• the output produced the experimental --json option

License

cargo-unmaintained is licensed and distributed under the AGPLv3 license. Contact us if you're looking for an exception to the terms.