Crypt::OpenSSL::X509 versions before 2.1.3 for Perl allow a heap out-of-bounds read via a long certificate extension OID in hvexts.

When building the extension hash (via extensions(), extensionsbylongname(), extensionsbyoid(), or hasextensionoid()), the code passes OBJobj2txt()'s return value as the hash-key length; because that value is the OID's full text length rather than the bytes written to the fixed-size buffer (129 bytes), an OID whose text is longer than the 129-byte buffer causes a read past the allocation, exposing adjacent heap memory as the returned hash key. extensionsbyname() uses the static shortname path and is not affected.

Crypt::OpenSSL::X509 versions before 2.1.3 for Perl allow denial of service via NULL pointer dereference.

X509V3EXTd2i(ext) returns NULL when an extension's DER value fails to parse. basicC, ia5string, and authatt dereference its result without a NULL check. keyiddata also dereferences akid->keyid, which is NULL for an empty AKI SEQUENCE (DER 30 00) even when the parse succeeds.

A caller invoking an affected helper on an extension from an untrusted certificate triggers a SIGSEGV that crashes the Perl process.