RUSTSEC-2021-0125: Panic on incorrect date input to `simple_asn1`

What to do

1. See which version you have: cargo tree -i simple_asn1 (it also shows which of your dependencies pulls it in).
2. Update within your version requirement: cargo update -p simple_asn1. If the fix is a newer major or minor than your requirement allows, raise it in Cargo.toml (for example simple_asn1 = "0.6.1") or update the dependency that pulls it in.
3. Check again with cargo audit, or paste your Cargo.lock into our Cargo.toml checker.

Details from the advisory

Version 0.6.0 of the simple_asn1 crate panics on certain malformed inputs to its parsing functions, including from_der and der_decode. Because this crate is frequently used with inputs from the network, this should be considered a security vulnerability.

The issue occurs when parsing the old ASN.1 "UTCTime" time format. If an attacker provides a UTCTime where the first character is ASCII but the second character is above 0x7f, a string slice operation in the from_der_ function will try to slice into the middle of a UTF-8 character, and cause a panic.

This error was introduced in commit d7d39d709577710e9dc8, which updated simple_asn1 to use time instead of chrono because of RUSTSEC-2020-159. Versions of simple_asn1 before 0.6.0 are not affected by this issue.

The patch was applied in simple_asn1 version 0.6.1.

References

• Package: crates.io/crates/simple_asn1
• Advisory: rustsec.org/advisories/RUSTSEC-2021-0125.html
• Report: github.com/acw/simple_asn1/issues/27

From the RustSec Advisory Database (CC0-1.0) via the OSV export, downloaded Oct 24, 2026. Severity score computed from the published CVSS vector.