Vulnerability HighRUSTSEC-2016-0001 · openssl
RUSTSEC-2016-0001: SSL/TLS MitM vulnerability due to insecure defaults
Short answerA security vulnerability in the openssl crate: SSL/TLS MitM vulnerability due to insecure defaults. High severity (CVSS 8.1). Fixed in 0.9.0: update to a fixed version.
| Crate | openssl |
|---|---|
| Type | Vulnerability |
| Affected versions | Before 0.9.0. |
| Fixed in | 0.9.0 |
| Severity | High, CVSS 8.1 CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H |
| Published | 2016-11-05 |
| Last changed | 2026-02-04 |
| Also known as | CVE-2016-10931, GHSA-34p9-f4q3-c4r7 |
What to do
- See which version you have:
cargo tree -i openssl(it also shows which of your dependencies pulls it in). - Update within your version requirement:
cargo update -p openssl. If the fix is a newer major or minor than your requirement allows, raise it in Cargo.toml (for exampleopenssl = "0.9.0") or update the dependency that pulls it in. - Check again with
cargo audit, or paste your Cargo.lock into our Cargo.toml checker.
Details from the advisory
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).
References
- Package: crates.io/crates/openssl
- Advisory: rustsec.org/advisories/RUSTSEC-2016-0001.html
- Web: github.com/sfackler/rust-openssl/releases/tag/v0.9.0
From the RustSec Advisory Database (CC0-1.0) via the OSV export, downloaded Oct 24, 2026. Severity score computed from the published CVSS vector.
Other advisories for openssl
- Vulnerability CriticalRUSTSEC-2018-0010 · 2018-06-01Use after free in CMS Signing
- VulnerabilityRUSTSEC-2023-0022 · 2023-03-24`openssl` `X509NameBuilder::build` returned object is not thread safe
- VulnerabilityRUSTSEC-2023-0023 · 2023-03-24`openssl` `SubjectAlternativeName` and `ExtendedKeyUsage::other` allow arbitrary file read
- VulnerabilityRUSTSEC-2023-0024 · 2023-03-24`openssl` `X509Extension::new` and `X509Extension::new_nid` null pointer dereference
- VulnerabilityRUSTSEC-2023-0044 · 2023-06-20`openssl` `X509VerifyParamRef::set_host` buffer over-read
- UnsoundRUSTSEC-2023-0072 · 2023-11-23`openssl` `X509StoreRef::objects` is unsound
- VulnerabilityRUSTSEC-2024-0357 · 2024-07-21`MemBio::get_buf` has undefined behavior with empty buffers
- VulnerabilityRUSTSEC-2025-0004 · 2025-02-02ssl::select_next_proto use after free
Up next
Same crateopenssl: security historyEvery advisory for this crate, and whether it is safe to use today.Read it next →Did this answer your question?