Headline
GHSA-r5w3-xm58-jv6j: Cargo did not verify SSH host keys
The Rust Security Response WG was notified that Cargo did not perform SSH host key verification when cloning indexes and dependencies via SSH. An attacker could exploit this to perform man-in-the-middle (MITM) attacks.
This vulnerability has been assigned CVE-2022-46176.
Overview
When an SSH client establishes communication with a server, to prevent MITM attacks the client should check whether it already communicated with that server in the past and what the server’s public key was back then. If the key changed since the last connection, the connection must be aborted as a MITM attack is likely taking place.
It was discovered that Cargo never implemented such checks, and performed no validation on the server’s public key, leaving Cargo users vulnerable to MITM attacks.
Affected Versions
All Rust versions containing Cargo before 1.66.1 are vulnerable.
Note that even if you don’t explicitly use SSH for alternate registry indexes or crate dependencies, you might be affected by this vulnerability if you have configured git to replace HTTPS connections to GitHub with SSH (through git’s [url.<base>.insteadOf][1] setting), as that’d cause you to clone the crates.io index through SSH.
Mitigations
We will be releasing Rust 1.66.1 today, 2023-01-10, changing Cargo to check the SSH host key and abort the connection if the server’s public key is not already trusted. We recommend everyone to upgrade as soon as possible.
Patch files for Rust 1.66.0 are also available here for custom-built toolchains.
For the time being Cargo will not ask the user whether to trust a server’s public key during the first connection. Instead, Cargo will show an error message detailing how to add that public key to the list of trusted keys. Note that this might break your automated builds if the hosts you clone dependencies or indexes from are not already trusted.
The Rust Security Response WG was notified that Cargo did not perform SSH host key verification when cloning indexes and dependencies via SSH. An attacker could exploit this to perform man-in-the-middle (MITM) attacks.
This vulnerability has been assigned CVE-2022-46176.
Overview
When an SSH client establishes communication with a server, to prevent MITM attacks the client should check whether it already communicated with that server in the past and what the server’s public key was back then. If the key changed since the last connection, the connection must be aborted as a MITM attack is likely taking place.
It was discovered that Cargo never implemented such checks, and performed no validation on the server’s public key, leaving Cargo users vulnerable to MITM attacks.
Affected Versions
All Rust versions containing Cargo before 1.66.1 are vulnerable.
Note that even if you don’t explicitly use SSH for alternate registry indexes or crate dependencies, you might be affected by this vulnerability if you have configured git to replace HTTPS connections to GitHub with SSH (through git’s [url.<base>.insteadOf][1] setting), as that’d cause you to clone the crates.io index through SSH.
Mitigations
We will be releasing Rust 1.66.1 today, 2023-01-10, changing Cargo to check the SSH host key and abort the connection if the server’s public key is not already trusted. We recommend everyone to upgrade as soon as possible.
Patch files for Rust 1.66.0 are also available here for custom-built toolchains.
For the time being Cargo will not ask the user whether to trust a server’s public key during the first connection. Instead, Cargo will show an error message detailing how to add that public key to the list of trusted keys. Note that this might break your automated builds if the hosts you clone dependencies or indexes from are not already trusted.
References
- GHSA-r5w3-xm58-jv6j
- https://git-scm.com/docs/git-config#Documentation/git-config.txt-urlltbasegtinsteadOf
- https://github.com/rust-lang/wg-security-response/tree/main/patches/CVE-2022-46176
- https://www.rust-lang.org/policies/security
Related news
Cargo is a Rust package manager. The Rust Security Response WG was notified that Cargo did not perform SSH host key verification when cloning indexes and dependencies via SSH. An attacker could exploit this to perform man-in-the-middle (MITM) attacks. This vulnerability has been assigned CVE-2022-46176. All Rust versions containing Cargo before 1.66.1 are vulnerable. Note that even if you don't explicitly use SSH for alternate registry indexes or crate dependencies, you might be affected by this vulnerability if you have configured git to replace HTTPS connections to GitHub with SSH (through git's [`url.<base>.insteadOf`][1] setting), as that'd cause you to clone the crates.io index through SSH. Rust 1.66.1 will ensure Cargo checks the SSH host key and abort the connection if the server's public key is not already trusted. We recommend everyone to upgrade as soon as possible.