Improper Certificate Validation in openssl

published 2016-11-05 10y ago modified 2026-06-17 4mo ago also GHSA-34p9-f4q3-c4r7 , RUSTSEC-2016-0001 , EUVD-2021-1528

cvss: 8.1; version 3.0, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 0.7%; EPSS 0.7% chance of exploitation in 30 days, percentile 55%
public exploits: 0; none known

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.

Patch / fix

fixed in 2 links 1

crates.io openssl 0.9.0
rust-openssl_project rust-openssl 0.9.0

github.com/sfackler/rust-openssl/releases/tag/v0.9.0 release

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Exploit prediction

0.75% chance of exploitation in the next 30 days, higher than 55% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by	version	score	vector
NVD	3.0	8.1	CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD	2.0	6.8	AV:N/AC:M/Au:N/C:P/I:P/A:P
OSV	3.0	8.1	CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
GitHub	3.0	8.1	CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected packages

ecosystem	package	affected	fixed in
crates.io	openssl	<0.9.0 >=0.0.0-0, <0.9.0	0.9.0

Classification

Weakness

CWE-295 Improper Certificate Validation

References

rustsec.org /advisories/RUSTSEC-2016-0001.html
web, release-notes, vendor-advisory, advisory
nvd.nist.gov /vuln/detail/CVE-2016-10931
advisory
github.com /sfackler/rust-openssl
package
github.com /sfackler/rust-openssl/releases/tag/v0.9.0
web
crates.io /crates/openssl
package

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.