CVE-2023-40030: Cargo downloads a Rust project’s dependencies and compiles the project. Starting in Rust 1.60.0 and prior to 1.72, Cargo did not escape Cargo feature ...

Description

Cargo downloads a Rust project’s dependencies and compiles the project. Starting in Rust 1.60.0 and prior to 1.72, Cargo did not escape Cargo feature names when including them in the report generated by `cargo build --timings`. A malicious package included as a dependency may inject nearly arbitrary HTML here, potentially leading to cross-site scripting if the report is subsequently uploaded somewhere. The vulnerability affects users relying on dependencies from git, local paths, or alternative registries. Users who solely depend on crates.io are unaffected. Rust 1.60.0 introduced `cargo build --timings`, which produces a report of how long the different steps of the build process took. It includes lists of Cargo features for each crate. Prior to Rust 1.72, Cargo feature names were allowed to contain almost any characters (with some exceptions as used by the feature syntax), but it would produce a future incompatibility warning about them since Rust 1.49. crates.io is far more stringent about what it considers a valid feature name and has not allowed such feature names. As the feature names were included unescaped in the timings report, they could be used to inject Javascript into the page, for example with a feature name like `features = ["<img src='' onerror=alert(0)"]`. If this report were subsequently uploaded to a domain that uses credentials, the injected Javascript could access resources from the website visitor. This issue was fixed in Rust 1.72 by turning the future incompatibility warning into an error. Users should still exercise care in which package they download, by only including trusted dependencies in their projects. Please note that even with these vulnerabilities fixed, by design Cargo allows arbitrary code execution at build time thanks to build scripts and procedural macros: a malicious dependency will be able to cause damage regardless of these vulnerabilities. crates.io has server-side checks preventing this attack, and there are no packages on crates.io exploiting these vulnerabilities. crates.io users still need to excercise care in choosing their dependencies though, as remote code execution is allowed by design there as well.

Metrics

CVSS 3.1

6.1/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

EPSS Probability

0.85%

53.4th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-79

Affected Software

Vendor	Product	Versions
Rust-Lang	Rust	>= 1.60.0, < 1.72.0

References

Timeline

Published: Aug 24, 2023
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2023-40030?

Cargo downloads a Rust project’s dependencies and compiles the project. Starting in Rust 1.60.0 and prior to 1.72, Cargo did not escape Cargo feature names when including them in the report generated by `cargo build --timings`. A malicious package included as a dependency may inject nearly arbitrary HTML here, potentially leading to cross-site scripting if the report is subsequently uploaded somewhere. The vulnerability affects users relying on dependencies from git, local paths, or alternative registries. Users who solely depend on crates.io are unaffected. Rust 1.60.0 introduced `cargo build --timings`, which produces a report of how long the different steps of the build process took. It includes lists of Cargo features for each crate. Prior to Rust 1.72, Cargo feature names were allowed to contain almost any characters (with some exceptions as used by the feature syntax), but it would produce a future incompatibility warning about them since Rust 1.49. crates.io is far more stringent about what it considers a valid feature name and has not allowed such feature names. As the feature names were included unescaped in the timings report, they could be used to inject Javascript into the page, for example with a feature name like `features = ["<img src='' onerror=alert(0)"]`. If this report were subsequently uploaded to a domain that uses credentials, the injected Javascript could access resources from the website visitor. This issue was fixed in Rust 1.72 by turning the future incompatibility warning into an error. Users should still exercise care in which package they download, by only including trusted dependencies in their projects. Please note that even with these vulnerabilities fixed, by design Cargo allows arbitrary code execution at build time thanks to build scripts and procedural macros: a malicious dependency will be able to cause damage regardless of these vulnerabilities. crates.io has server-side checks preventing this attack, and there are no packages on crates.io exploiting these vulnerabilities. crates.io users still need to excercise care in choosing their dependencies though, as remote code execution is allowed by design there as well.

How severe is CVE-2023-40030?

CVE-2023-40030 has a CVSS score of 6.1/10 (MEDIUM severity). The EPSS model estimates a 0.85% probability of exploitation in the next 30 days.

How do I fix CVE-2023-40030?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

How Strix Helps

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