CVE-2016-10931
Improper Certificate Validation in openssl
An issue was discovered in the openssl crate before 0.9.0 for Rust. There is an SSL/TLS man-in-the-middle vulnerability because certificate verification is off by default and there is no API for hostname verification.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Exploit likelihood
What each source reports
NVD Score used
An issue was discovered in the openssl crate before 0.9.0 for Rust. There is an SSL/TLS man-in-the-middle vulnerability because certificate verification is off by default and there is no API for hostname verification.
- Record
CVE-2016-10931- CVSS 3.0
- 8.1 High
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H - CVSS 2.0
- 6.8 Medium
AV:N/AC:M/Au:N/C:P/I:P/A:P - Weakness
- CWE-295
- Updated
- 2026-11-02
CVE List No score
An issue was discovered in the openssl crate before 0.9.0 for Rust. There is an SSL/TLS man-in-the-middle vulnerability because certificate verification is off by default and there is no API for hostname verification.
- Record
CVE-2016-10931- Updated
- 2026-11-02
EUVDEUVD-2021-1528 No score
An issue was discovered in the openssl crate before 0.9.0 for Rust. There is an SSL/TLS man-in-the-middle vulnerability because certificate verification is off by default and there is no API for hostname verification.
- Record
EUVD-2021-1528- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-34p9-f4q3-c4r7
Improper Certificate Validation in openssl
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).
- Record
GHSA-34p9-f4q3-c4r7- CVSS 3.0
- 8.1 High
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-295
- Updated
- 2026-11-02
OSV
An issue was discovered in the openssl crate before 0.9.0 for Rust. There is an SSL/TLS man-in-the-middle vulnerability because certificate verification is off by default and there is no API for hostname verification.
- Record
CVE-2016-10931- CVSS 3.0
- 8.1 High
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
OSVGHSA-34p9-f4q3-c4r7
Improper Certificate Validation in openssl
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).
- Record
GHSA-34p9-f4q3-c4r7- CVSS 3.0
- 8.1 High
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-295
- Updated
- 2026-11-02
OSVRUSTSEC-2016-0001
SSL/TLS MitM vulnerability due to insecure defaults
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).
- Record
RUSTSEC-2016-0001- CVSS 3.0
- 8.1 High
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
Affected products
Affected packages
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2016-10931 is a high vulnerability (CVSS 8.1) in Rust-openssl Project Rust-openssl, published November 5, 2016. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.74%, the 55th percentile. Fixed in openssl 0.9.0.