Chrono has potential segfault issue in SPIFFE authenticator

Summary

### Impact Several vulnerabilities have been reported in the `time` and `chrono` crates related to handling of calls to `localtime_r`. You can follow some of the discussions [here](https://github.com/chronotope/chrono/issues/602) and [here](https://github.com/time-rs/time/issues/293), and the associated CVE [here](https://nvd.nist.gov/vuln/detail/CVE-2020-26235). In our case, the issue with the dependency was flagged by our nightly CI build running [`cargo-audit`](https://github.com/parallaxsecond/parsec/issues/544). The vulnerability leads to a segfault in specific circumstances - namely, when one of a number of functions in the `time` crate is called while any other thread is setting an environment variable. Given that in the case of the Parsec service this affects the SPIFFE authenticator, Parsec service users can encounter the issue only when the JWT SVID authenticator is enabled and being used. We have not undergone any manual tracing to understand if the vulnerable methods are called anywhere in our stack, however it seems reasonable to expect that if that were to be the case, the issue would lie in JWT validation (i.e. when handling the dates found within a Json Web Token). JWT validation could thus fail, bringing down the thread in which the request happens. The rest of the threads continue to work. Since the threadpool implementation that we use [continues replenishing the pool](https://docs.rs/threadpool/latest/threadpool/) when one thread panics, the impact on the service should be minimal. ### Patches No current patches exist as the problems lie in a number of dependencies that are not under our control (see more details [here](https://github.com/parallaxsecond/parsec/issues/544#issuecomment-1024185688)). The issue tracking the required change in the `rust-spiffe` crate (through which the vulnerable dependencies are imported in Parsec) can be seen [here](https://github.com/maxlambrecht/rust-spiffe/issues/17). Once updates happen in our dependency chain that allow us to update beyond the vulnerable versions of `time` and `chrono`, a new version of the Parsec service will be tagged and released with the appropriate notifications. ### Workarounds The only complete workaround is to use a different type of authenticator with the Parsec service. ### References As quoted in the initial paragraph, you can find out more information: * in the `chrono` repo issue [here](https://github.com/chronotope/chrono/issues/602) * in the `time` repo issue [here](https://github.com/time-rs/time/issues/293) * in the official CVE report [here](https://nvd.nist.gov/vuln/detail/CVE-2020-26235) * in our tracking issue [here](https://github.com/parallaxsecond/parsec/issues/544) ### For more information: If you have any questions or comments about this advisory: * Open an issue in [the Parsec service repo](https://github.com/parallaxsecond/parsec) * Email us at [[email protected]](mailto:[email protected])