Impact

The affected functions set environment variables without synchronization. On Unix-like operating systems, this can crash in multithreaded programs. Programs may segfault due to dereferencing a dangling pointer if an environment variable is read in a different thread than the affected functions. This may occur without the user's knowledge, notably in the Rust standard library or third-party libraries.

The affected functions from time 0.2.7 through 0.2.22 are:

• time::UtcOffset::local_offset_at
• time::UtcOffset::try_local_offset_at
• time::UtcOffset::current_local_offset
• time::UtcOffset::try_current_local_offset
• time::OffsetDateTime::now_local
• time::OffsetDateTime::try_now_local

The affected functions in time 0.1 (all versions) are:

• time::at_utc
• time::at
• time::now
• time::tzset

Non-Unix targets (including Windows and wasm) are unaffected.

Patches

Pending a proper fix, the internal method that determines the local offset has been modified to always return None on the affected operating systems. This has the effect of returning an Err on the try_* methods and UTC on the non-try_* methods.

Users and library authors with time in their dependency tree should perform cargo update, which will pull in the updated, unaffected code.

Users of time 0.1 do not have a patch and should upgrade to an unaffected version: time 0.2.23 or greater or the 0.3 series.

Workarounds

A possible workaround for crates affected through the transitive dependency in chrono, is to avoid using the default oldtime feature dependency of the chrono crate by disabling its default-features and manually specifying the required features instead.

Examples:

Cargo.toml:

chrono = { version = "0.4", default-features = false, features = ["serde"] }

chrono = { version = "0.4.22", default-features = false, features = ["clock"] }

Commandline:

cargo add chrono --no-default-features -F clock

Sources:

• chronotope/chrono#602 (comment)
• vityafx/serde-aux#21

The git2 and libgit2-sys crates are Rust wrappers around the libgit2 C library. It was discovered that libgit2 1.5.0 and below did not verify SSH host keys when establishing an SSH connection, exposing users of the library to Man-In-the-Middle attacks.

The libgit2 team assigned CVE-2023-22742 to this vulnerability. The following versions of the libgit2-sys Rust crate have been released:

• libgit2-sys 0.14.2, updating the underlying libgit2 C library to version 1.5.1.
• libgit2-sys 0.13.5, updating the underlying libgit2 C library to version 1.4.5.

A new git2 crate version has also been released, 0.16.1. This version only bumps its libgit2-sys dependency to ensure no vulnerable libgit2-sys versions are used, but contains no code changes: if you update the libgit2-sys version there is no need to also update the git2 crate version.

You can learn more about this vulnerability in libgit2's advisory

The libgit2 project fixed three security issues in the 1.7.2 release. These issues are:

• The git_revparse_single function can potentially enter an infinite loop on a well-crafted input, potentially causing a Denial of Service. This function is exposed in the git2 crate via the Repository::revparse_single method.
• The git_index_add function may cause heap corruption and possibly lead to arbitrary code execution. This function is exposed in the git2 crate via the Index::add method.
• The smart transport negotiation may experience an out-of-bounds read when a remote server did not advertise capabilities.

The libgit2-sys crate bundles libgit2, or optionally links to a system libgit2 library. In either case, versions of the libgit2 library less than 1.7.2 are vulnerable. The 0.16.2 release of libgit2-sys bundles the fixed version of 1.7.2, and requires a system libgit2 version of at least 1.7.2.

It is recommended that all users upgrade.