Quick overview

The Rust team was recently notified of a security vulnerability affecting rustdoc plugins. If you are not using rustdoc plugins, you are not affected. We’re not aware of any usage of this feature. The associated CVE is CVE-2018-1000622.

You can find the full announcement on our rustlang-security-announcements mailing list here.

Announcement

On Tuesday July 3rd, Red Hat reported a security vulnerability in rustdoc to us. The problem was in rustdoc’s obscure plugin functionality, consisting of its loading plugins from a path that is globally writable on most platforms, /tmp/rustdoc/plugins. This feature permitted a malicious actor to write a dynamic library into this path and have another user execute that code. The security issue only happens if you’re actively using the feature, and so this behavior will be removed from rustdoc in the near future, with patches landing for each channel over the next week. The plugin infrastructure predates 1.0 and is not usable on stable or nightly Rust today. Its removal should not impact any Rust users.

As Rust’s first official CVE, this is somewhat of a milestone for us. The fix will be out in 1.27.1 on Tuesday July 10th. Because there’s no embargo, we are filing for a CVE now, and will update this post with the number once we are assigned one.

Despite the acknowledge low impact and severity of this bug, the Rust team decided to follow the full procedure we have for security bugs. We know of no one who uses this functionality, so we felt comfortable discussing it publicly ahead of the patch release. The impact is limited due to the plugin functionality being long deprecated and being unusable on all current versions of Rust, as the required library is not shipped to users. However, since the bug can potentially cause problems for users, we decided to include this in the 1.27.1 stable release.

It’s worth noting that while Rust does prevent a lot of issues in your code at compile time, they’re issues that result from memory unsafety. This bug is a logic error. Rust code is not inherently secure, or bug-free. Sometimes, people get enthusiastic and make overly-broad claims about Rust, and this incident is a good demonstration of how Rust’s guarantees can’t prevent all bugs.

Thank you to Red Hat for responsibly disclosing the problem and working with us to ensure that the fix we plan to ship is correct.