Affected versions of this crate passes an uninitialized buffer to a user-provided Read implementation.
Arbitrary Read implementations can read from the uninitialized buffer (memory exposure) and also can return incorrect number of bytes written to the buffer. Reading from uninitialized memory produces undefined values that can quickly invoke undefined behavior.
The problem was fixed in commit cdff034
by zero-initializing the buffer before passing it to a user-provided Read implementation.
github.com/tectonic-typesetting/tectonic
github.com/tectonic-typesetting/tectonic/commit/cdff034e6d93cdfdafd13d8c6956e22fa5a57b79
github.com/tectonic-typesetting/tectonic/issues/752
nvd.nist.gov/vuln/detail/CVE-2021-45703
raw.githubusercontent.com/rustsec/advisory-db/main/crates/tectonic_xdv/RUSTSEC-2021-0112.md
rustsec.org/advisories/RUSTSEC-2021-0112.html