CVE-2021-3450 — openssl-src
HIGHCVE-2021-3450 is a high-severity (CVSS 7.4) CWE-295 vulnerability in openssl-src. EPSS puts its 30-day exploitation probability at 18.3% (97th percentile). A fix is available for openssl-src — see the affected versions and patch details below.
Certificate check bypass in openssl-src
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2021-3450 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 385,738 CVEs with a current EPSS score, this one falls in the 10–50% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
openssl-srcReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.
Description
The X509_V_FLAG_X509_STRICT flag enables additional security checks of the certificates present in a certificate chain. It is not set by default. Starting from OpenSSL version 1.1.1h a check to disallow certificates in the chain that have explicitly encoded elliptic curve parameters was added as an additional strict check. An error in the implementation of this check meant that the result of a previous check to confirm that certificates in the chain are valid CA certificates was overwritten. This effectively bypasses the check that non-CA certificates must not be able to issue other certificates. If a "purpose" has been configured then there is a subsequent opportunity for checks that the certificate is a valid CA. All of the named "purpose" values implemented in libcrypto perform this check. Therefore, where a purpose is set the certificate chain will still be rejected even when the strict flag has been used. A purpose is set by default in libssl client and server certificate verification routines, but it can be overridden or removed by an application. In order to be affected, an application must explicitly set the X509_V_FLAG_X509_STRICT verification flag and either not set a purpose for the certificate verification or, in the case of TLS client or server applications, override the default purpose. OpenSSL versions 1.1.1h and newer are affected by this issue. Users of these versions should upgrade to OpenSSL 1.1.1k. OpenSSL 1.0.2 is not impacted by this issue. Fixed in OpenSSL 1.1.1k (Affected 1.1.1h-1.1.1j).
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | openssl-src | ≥ 111.11.0&&< 111.15.0 | 111.15.0cargo update -p openssl-src --precise 111.15.0 |
Affected Products
fedorafedoraprojectfreebsdfreebsdweb gatewaymcafeeweb gateway cloud servicemcafeecloud volumes ontap mediatornetapponcommand workflow automationnetappDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for openssl-src, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update openssl-src to 111.15.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-3450 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
This flaw affects openssl 1.1.1h and above only, older versions are not affected by this flaw.
The following conditions have to be met for an application compiled with OpenSSL to be vulnerable: - the CA trusted by the system must issue or have issued certificates that don't include basic Key Usage extension. - the CA certificates must not have path length constraint set to a value that would limit the certificate chain to just the subscriber certificates (i.e. CA certificate just above the subscriber cert must not have 0 as the path length constraint, and any CA above it must not have it increase by more than 1 for every level in the hierarchy) - the attacker needs to have access to such subscriber certificate (without basic Key Usage and linking up to CAs without path length…Source: Red Hat security advisory for CVE-2021-3450 (CC BY 4.0)
| Product | Fixed in | Advisory |
|---|---|---|
| JBCS 2.4.37 SP7 | openssl | RHSA-2021:1200 |
| JBoss Core Services on RHEL 7 | jbcs-httpd24-httpd-0:2.4.37-70.jbcs.el7 | RHSA-2021:1199 |
| Red Hat Enterprise Linux 8 | openssl-1:1.1.1g-15.el8_3 | RHSA-2021:1024 |
| Red Hat JBoss Web Server 3.1 | openssl | RHSA-2021:1203 |
| Red Hat JBoss Web Server 3 for RHEL 7 | tomcat-native-0:1.2.23-24.redhat_24.ep7.el7 | RHSA-2021:1202 |
| Red Hat JBoss Web Server 5 | see advisory | RHSA-2021:1196 |
| Red Hat JBoss Web Server 5.4 on RHEL 7 | jws5-tomcat-native-0:1.2.25-4.redhat_4.el7jws | RHSA-2021:1195 |
| Red Hat Virtualization 4 for Red Hat Enterprise Linux 8 | redhat-virtualization-host-0:4.4.5-20210330.0.el8_3 | RHSA-2021:1189 |
Frequently Asked Questions
Is CVE-2021-3450 in your dependencies?
Find it across crates.io, including transitive dependencies.