What’s Vulnerable › Vulnerabilities

CVE-2021-23841: Null pointer deref in X509_issuer_and_serial_hash()

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 1.0.2 should upgrade to 1.0.2y. Other users should upgrade to 1.1.1j. Fixed in OpenSSL 1.1.1j (Affected 1.1.1-1.1.1i). Fixed in OpenSSL 1.0.2y (Affected 1.0.2-1.0.2x).

Affected products

How to fix

Upgrade to a fixed version: Apple iPadOS 14.6; Apple Iphone Os 14.6; Apple macOS 11.4; Apple Safari 14.1.1; OpenSSL 1.0.2y, 1.1.1j; Oracle Corporation MySQL Enterprise Monitor 8.0.23; MySQL Server 5.7.33, 8.0.23; Siemens SINEC INS 1.0. Check the vendor advisory for mitigations.

References

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