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NVD / CVE Program· CNA openssl

CVE-2021-3450: CA certificate check bypass with X509_V_FLAG_X509_STRICT

Noroxi assessment

Priority: Monitor (action score 35/100)

  • Public proof-of-concept code exists (GitHub); there is no record of exploitation in the wild.
  • Probability of exploitation in the next 30 days: 18.3% (FIRST EPSS); higher than 97.2% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. Special conditions such as timing or configuration are required.
  • According to CISA the attack is automatable: targets can be found by mass scanning.
  • Fixed version: openssl (Alpine:v3.10) 1.1.1k-r0; openssl3 (Alpine:v3.15) 1.1.1k-r0; openssl-src (crates.io) 111.15.0.
  • Mentioned 6 times in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to openssl (Alpine:v3.10) 1.1.1k-r0; openssl3 (Alpine:v3.15) 1.1.1k-r0; openssl-src (crates.io) 111.15.0 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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).

HighCVSS 7.4 · v3.1—Proof of concept Fix available
Published
Mar 25, 2021
Updated
Oct 8, 2026
EPSS
18.3% · 97th percentile

Report tools

JSON

Action score

35

Monitor

Low priority for now.

CVSS
29 / 40 · 7.4 / 10
CISA KEV
0 / 30 · Not listed
EPSS
6 / 30 · 18.3%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • Proof of concept exists, no weaponized module
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

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When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
opensslopenssl
oraclemysql connectors
oraclejd edwards world security
freebsdfreebsd
netappsantricity smi-s provider firmware
netappsantricity smi-s provider
netappstoragegrid firmware
netappstoragegrid
windriverlinux
netappcloud volumes ontap mediator
netapponcommand workflow automation
netappontap select deploy administration utility

and 23 more

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Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • fedoraproject fedora34
  • freebsd freebsd12.2
  • mcafee web gateway10.1.1
  • mcafee web gateway8.2.19
  • mcafee web gateway9.2.10
  • mcafee web gateway cloud service10.1.1
  • mcafee web gateway cloud service8.2.19
  • mcafee web gateway cloud service9.2.10
  • netapp cloud volumes ontap mediatorall versions
  • netapp oncommand workflow automationall versions
  • netapp ontap select deploy administration utilityall versions
  • netapp santricity smi-s provider firmwareall versions
  • netapp storagegridall versions
  • netapp storagegrid firmwareall versions
  • nodejs node.js15.0.0 and later · before 15.14.0
  • nodejs node.js14.0.0 and later · before 14.16.1
  • nodejs node.js10.0.0 and later · before 10.24.1
  • nodejs node.js12.0.0 and later · before 12.22.1
  • openssl openssl1.1.1h and later · before 1.1.1k
  • oracle commerce guided search11.3.2

Versions reported by the vendor

Affected version ranges reported by the assigning authority (openssl). Independent of NVD's CPE analysis and usually ahead of it.

  • OpenSSL OpenSSL

    • Fixed in OpenSSL 1.1.1k (Affected 1.1.1h-1.1.1j)affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Alpine:v3.10opensslfrom 1.1.1h · before 1.1.1k-r01.1.1k-r0
Alpine:v3.15openssl3before 1.1.1k-r01.1.1k-r0
crates.ioopenssl-srcfrom 111.11.0 · before 111.15.0111.15.0
Debian:12opensslbefore 1.1.1k-11.1.1k-1
openSUSE:Leap 15.2nodejs10before 10.24.1-lp152.2.15.110.24.1-lp152.2.15.1
openSUSE:Leap 15.2nodejs12before 12.22.2-lp152.3.15.112.22.2-lp152.3.15.1
openSUSE:Leap 15.3nodejs10before 10.24.1-1.36.110.24.1-1.36.1
openSUSE:Leap 15.3nodejs12before 12.22.2-4.16.112.22.2-4.16.1
Red Hat:enterprise_linux:8::baseosopensslbefore 1:1.1.1g-15.el8_31:1.1.1g-15.el8_3
Red Hat:enterprise_linux:8::baseosopenssl-debuginfobefore 1:1.1.1g-15.el8_31:1.1.1g-15.el8_3
Red Hat:enterprise_linux:8::baseosopenssl-debugsourcebefore 1:1.1.1g-15.el8_31:1.1.1g-15.el8_3
Red Hat:enterprise_linux:8::baseosopenssl-develbefore 1:1.1.1g-15.el8_31:1.1.1g-15.el8_3
Red Hat:enterprise_linux:8::baseosopenssl-libsbefore 1:1.1.1g-15.el8_31:1.1.1g-15.el8_3
Red Hat:enterprise_linux:8::baseosopenssl-libs-debuginfobefore 1:1.1.1g-15.el8_31:1.1.1g-15.el8_3
Red Hat:enterprise_linux:8::baseosopenssl-perlbefore 1:1.1.1g-15.el8_31:1.1.1g-15.el8_3
Red Hat:jboss_core_services:1::el7jbcs-httpd24-httpdbefore 0:2.4.37-70.jbcs.el70:2.4.37-70.jbcs.el7
Red Hat:jboss_core_services:1::el7jbcs-httpd24-httpd-debuginfobefore 0:2.4.37-70.jbcs.el70:2.4.37-70.jbcs.el7
Red Hat:jboss_core_services:1::el7jbcs-httpd24-httpd-develbefore 0:2.4.37-70.jbcs.el70:2.4.37-70.jbcs.el7
Red Hat:jboss_core_services:1::el7jbcs-httpd24-httpd-manualbefore 0:2.4.37-70.jbcs.el70:2.4.37-70.jbcs.el7
Red Hat:jboss_core_services:1::el7jbcs-httpd24-httpd-selinuxbefore 0:2.4.37-70.jbcs.el70:2.4.37-70.jbcs.el7
Red Hat:jboss_core_services:1::el7jbcs-httpd24-httpd-toolsbefore 0:2.4.37-70.jbcs.el70:2.4.37-70.jbcs.el7
Red Hat:jboss_core_services:1::el7jbcs-httpd24-mod_cluster-nativebefore 0:1.3.14-20.Final_redhat_2.jbcs.el70:1.3.14-20.Final_redhat_2.jbcs.el7
Red Hat:jboss_core_services:1::el7jbcs-httpd24-mod_cluster-native-debuginfobefore 0:1.3.14-20.Final_redhat_2.jbcs.el70:1.3.14-20.Final_redhat_2.jbcs.el7
Red Hat:jboss_core_services:1::el7jbcs-httpd24-mod_http2before 0:1.15.7-14.jbcs.el70:1.15.7-14.jbcs.el7

+39

Same product

openssl: all records

Other highest-scoring records for the same primary product.

  • CVE-2014-0160The (1) TLS and (2) DTLS implementations in OpenSSL 1.0.1 before 1.0.1g do not properly handle Heartbeat Extension packets, which allows remKEV
    90Now
  • CVE-2021-3711SM2 Decryption Buffer Overflow
    65This week
  • CVE-2003-0545Double free vulnerability in OpenSSL 0.9.7 allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code
    65This week

Published before and after this one in the same product

  • ← EarlierCVE-2021-23841Feb 16, 2021 · Null pointer deref in X509_issuer_and_serial_hash()
    25Monitor
  • ← EarlierCVE-2021-3449Mar 25, 2021 · NULL pointer deref in signature_algorithms processing
    42Plan
  • Later →CVE-2021-3712Aug 24, 2021 · Read buffer overruns processing ASN.1 strings
    44Plan

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
alpine:openssl1.1.1k-r0 · Alpine:v3.10Package registry (OSV)
alpine:openssl31.1.1k-r0 · Alpine:v3.15Package registry (OSV)
crates.io:openssl-src111.15.0Package registry (OSV)
debian:openssl1.1.1k-1 · Debian:12Package registry (OSV)
opensuse:nodejs1010.24.1-lp152.2.15.1 · openSUSE:Leap 15.2Package registry (OSV)
opensuse:nodejs1212.22.2-lp152.3.15.1 · openSUSE:Leap 15.2Package registry (OSV)
red hat:jbcs-httpd24-httpd0:2.4.37-70.jbcs.el7 · Red Hat:jboss_core_services:1::el7Package registry (OSV)
red hat:jws5-tomcat-native0:1.2.25-4.redhat_4.el7jws · Red Hat:jboss_enterprise_web_server:5.4::el7Package registry (OSV)
red hat:jws5-tomcat-native-debuginfo0:1.2.25-4.redhat_4.el7jws · Red Hat:jboss_enterprise_web_server:5.4::el7Package registry (OSV)
red hat:openssl1:1.1.1g-15.el8_3 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:openssl-debuginfo1:1.1.1g-15.el8_3 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:openssl-debugsource1:1.1.1g-15.el8_3 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:openssl-devel1:1.1.1g-15.el8_3 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:openssl-libs1:1.1.1g-15.el8_3 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:openssl-libs-debuginfo1:1.1.1g-15.el8_3 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:openssl-perl1:1.1.1g-15.el8_3 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:redhat-virtualization-host0:4.4.5-20210330.0.el8_3 · Red Hat:rhev_hypervisor:4.4::el8Package registry (OSV)
red hat:redhat-virtualization-host-image-update0:4.4.5-20210330.0.el8_3 · Red Hat:rhev_hypervisor:4.4::el8Package registry (OSV)
rocky linux:openssl1:1.1.1g-15.el8_3 · Rocky Linux:8Package registry (OSV)
suse:nodejs1010.24.1-1.39.1 · SUSE:Linux Enterprise Module for Web and Scripting 12Package registry (OSV)
suse:nodejs1212.22.2-1.32.1 · SUSE:Linux Enterprise Module for Web and Scripting 12Package registry (OSV)

Exploit status

Proof of concept available

A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.

Evidence

  • Proof-of-concept repository on GitHub ×1

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
SourceKindDate
Proof-of-concept repository on GitHubstars:02026-06-23

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. Published
  2. First PoC+1915 d
  3. TodayNov 1, 2026+2046 d

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • Special conditions such as timing or configuration are required.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
none
Attack vector
Network
Attack complexity
High
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
None

Weakness class (CWE)

CWE-295 · Improper Certificate Validation

CVSS vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

nvd-primary

Root cause

A certificate validation error is silently swallowed instead of terminating the connection. Often, code added for a test environment makes its way into production.

The bug in code

The whole CWE-295 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

kotlin
override fun checkServerTrusted(chain: Array<X509Certificate>, type: String) {  // Left empty for the test environment}

Fixed

kotlin
val client = OkHttpClient.Builder()  .certificatePinner(    CertificatePinner.Builder()      .add("api.sirius.example", "sha256/…")      .build()  ).build()

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

  1. SSVC exploitation— → none
  2. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (19 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records