---
id: CVE-2026-5222
title: Cargo can be coerced to share credentials between registries
summary: Cargo can be coerced to share credentials between registries
severity: low
cwe:
  - CWE-647
vendor: cargo
product: cargo
ecosystem: rust
affected:
  - cargo < 0.97.0
patched:
  - cargo 0.97.0
published: '2026-06-26'
updated: '2026-06-26'
source: GHSA
sourceUrl: 'https://github.com/advisories/GHSA-p688-r7jv-fm6f'
references:
  - url: 'https://github.com/rust-lang/cargo/security/advisories/GHSA-p688-r7jv-fm6f'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-5222'
  - url: 'https://github.com/rust-lang/cargo/pull/17031'
  - url: 'https://blog.rust-lang.org/2026/05/25/cve-2026-5222'
  - url: 'https://groups.google.com/g/rustlang-security-announcements/c/SfUxOiIdY5s'
  - url: 'https://github.com/advisories/GHSA-p688-r7jv-fm6f'
tags:
  - ghsa
  - rust
epss: 0.00478
epssPercentile: 0.40409
ingestedAt: '2026-06-29T13:24:35.205Z'
---

## Overview

The Rust Security Response Team was notified that Cargo incorrectly normalized the URLs of third-party registries using the [sparse index protocol][1]. If a hosting provider allowed multiple registries to be hosted with arbitrary names within the same domain, an attacker able to publish crates in a registry could obtain the credentials of others users of the same registry.

This vulnerability is tracked as CVE-2026-5222. The severity of the vulnerability is **low**, due to the extremely niche requirements needed to achieve the attack.

## Overview

Originally Cargo only supported storing a registry's index within git repositories. Most git hosting solutions allow accessing a git repository with or without the `.git` suffix, so Cargo mirrored this behavior when normalizing registry URLs. This allowed credentials for `https://example.com/index` to be used for `https://example.com/index.git`.

This normalization was unintentionally applied to the new sparse indexes too. Sparse indexes can be hosted on any HTTPS server, which treat URLs ending with `.git` as different URLs than those without the suffix.

If the following conditions apply:

* `https://example.com/index` is a sparse index.
* `https://example.com/index` allows crates to depend on crates from any other registry.
* The attacker is able to publish crates on `https://example.com/index`.
* The attacker is able to upload arbitrary files to `https://example.com/index.git`.

...the attacker could configure `https://example.com/index.git` to be a Cargo sparse registry requiring authentication for downloads, and with a download URL pointing to a server recording any credentials set to it.

When the attacker then publishes a crate `foo` to `https://example.com/index` depending on a crate `bar` from `https://example.com/index.git`, and tricks the victim into downloading `foo`,  Cargo will think the two registries share the same credential and send the victim's Cargo token to the malicious registry.

## Mitigations

Rust 1.96, to be released on May 28th, 2026, will update Cargo to only strip the `.git` suffix from registry URLs using the git protocol. No mitigations are available for users of older versions of Cargo.

## Affected versions

All versions of Cargo shipped between Rust 1.68 (the stabilization of sparse registries) and 1.96 are affected.

## Acknowledgements

Cargo would like to thank Christos Papakonstantinou for reporting this issue according to the [Rust security policy][2].

Cargo also wants to thank the members of the Rust project who helped address the vulnerability: Arlo Siemens for developing the fix; Weihang Lo, Eric Huss and Emily Albini for reviewing the fix; Emily Albini for writing this advisory; Emily Albini, Josh Stone and Manish Goregaokar for coordinating the disclosure.

[1]: https://doc.rust-lang.org/cargo/reference/registries.html#registry-protocols
[2]: https://rust-lang.org/policies/security

## Affected packages

- `cargo < 0.97.0`

## Remediation

Upgrade to a patched release:

- `cargo 0.97.0`