All versions of rust-openssl prior to 0.9.0 contained numerous insecure defaults including off-by-default certificate verification and no API to perform hostname verification.

Unless configured correctly by a developer, these defaults could allow an attacker to perform man-in-the-middle attacks.

The problem was addressed in newer versions by enabling certificate verification by default and exposing APIs to perform hostname verification. Use the SslConnector and SslAcceptor types to take advantage of these new features (as opposed to the lower-level SslContext type).

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

When parsing JSON using json::Json::from_str, there is no limit to the depth of the stack, therefore deeply nested objects can cause a stack overflow, which aborts the process.

Example code that triggers the vulnerability is

fn main() {
    let _ = rustc_serialize::json::Json::from_str(&"[0,[".repeat(10000));
}

serde is recommended as a replacement to rustc_serialize.

OpenSSL has a modified bit that it can set on on X509_NAME objects. If this bit is set then the object is not thread-safe even when it appears the code is not modifying the value.

Thanks to David Benjamin (Google) for reporting this issue.

SubjectAlternativeName and ExtendedKeyUsage arguments were parsed using the OpenSSL function X509V3_EXT_nconf. This function parses all input using an OpenSSL mini-language which can perform arbitrary file reads.

Thanks to David Benjamin (Google) for reporting this issue.

These functions would crash when the context argument was None with certain extension types.

Thanks to David Benjamin (Google) for reporting this issue.

When this function was passed an empty string, openssl would attempt to call strlen on it, reading arbitrary memory until it reached a NUL byte.

Previously, MemBio::get_buf called slice::from_raw_parts with a null-pointer, which violates the functions invariants, leading to undefined behavior. In debug builds this would produce an assertion failure. This is now fixed.