CVE-2021-23841
5.9 · MEDIUMOverview
CVE-2021-23841 is a medium-severity vulnerability affecting openssl openssl. It was published on February 16, 2021 and has a CVSS 3.1 base score of 5.9 (MEDIUM).
This vulnerability has a CVSS 3.1 base score of 5.9, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical Description
The OpenSSL public API function X509_issuer_and_serial_hash() attempts to create a unique hash value based on the issuer and serial number data contained within an X509 certificate. However it fails to correctly handle any errors that may occur while parsing the issuer field (which might occur if the issuer field is maliciously constructed). This may subsequently result in a NULL pointer deref and a crash leading to a potential denial of service attack. The function X509_issuer_and_serial_hash() is never directly called by OpenSSL itself so applications are only vulnerable if they use this function directly and they use it on certificates that may have been obtained from untrusted sources. OpenSSL versions 1.1.1i and below are affected by this issue. Users of these versions should upgrade to OpenSSL 1.1.1j. OpenSSL versions 1.0.2x and below are affected by this issue. However OpenSSL 1.0.2 is out of support and no longer receiving public updates. Premium support customers of OpenSSL 1.
Remediation
Check the references section for vendor advisories and patches from openssl. Update openssl to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| openssl | openssl | >= 1.0.2, < 1.0.2y | Affected |
| tenable | tenable.sc | 5.13.0 | Affected |
| apple | safari | >= 0, < 14.1.1 | Affected |
| apple | ipados | >= 0, < 14.6 | Affected |
| apple | iphone_os | >= 0, < 14.6 | Affected |
| apple | macos | >= 11.1, < 11.4 | Affected |
| oracle | mysql_enterprise_monitor | >= 0, < 8.0.23 | Affected |
| oracle | mysql_server | >= 0, < 5.7.33 | Affected |
References
Frequently Asked Questions
What is CVE-2021-23841?
CVE-2021-23841 is a medium-severity vulnerability affecting openssl openssl. It was published on February 16, 2021 and has a CVSS 3.1 base score of 5.9 (MEDIUM).
How severe is CVE-2021-23841?
This vulnerability has a CVSS 3.1 base score of 5.9, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2021-23841?
Check the references section for vendor advisories and patches from openssl. Update openssl to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2021-23841?
CyberStrike's AI-powered security agents can automatically detect CVE-2021-23841 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
AI agents map your attack surface to find vulnerabilities like this one.
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