Affected versions of this crate suffered from an integer overflow bug when calculating the size of a buffer to use when encoding base64 using the encode_config_buf and encode_config functions. If the input string was large, this would cause a buffer to be allocated that was too small. Since this function writes to the buffer using unsafe code, it would allow an attacker to write beyond the buffer, causing memory corruption and possibly the execution of arbitrary code.

This flaw was corrected by using checked arithmetic to calculate the size of the buffer.

Affected versions contain multiple memory safety issues, such as:

• Unsoundly coercing immutable references to mutable references
• Unsoundly extending lifetimes of strings
• Adding the Send marker trait to objects that cannot be safely sent between threads

This may result in a variety of memory corruption scenarios, most likely use-after-free.

A significant refactoring effort has been conducted to resolve these issues.

Affected versions of this crate did not properly check if semantic tags were nested excessively during deserialization.

This allows an attacker to craft small (< 1 kB) CBOR documents that cause a stack overflow.

The flaw was corrected by limiting the allowed number of nested tags.

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

Lru crate has use after free vulnerability.

Lru crate has two functions for getting an iterator. Both iterators give references to key and value. Calling specific functions, like pop(), will remove and free the value, and but it's still possible to access the reference of value which is already dropped causing use after free.

When a Some(...) value was passed to the properties argument of either of these functions, a use-after-free would result.

In practice this would nearly always result in OpenSSL treating the properties as an empty string (due to CString::drop's behavior).

The maintainers thank quitbug for reporting this vulnerability to us.