The _gnutls_x509_verify_certificate function in lib/x509/verify.c in libgnutls in GnuTLS before 2.6.1 trusts certificate chains in which the last certificate is an arbitrary trusted, self-signed certificate, which allows man-in-the-middle attackers to insert a spoofed certificate for any Distinguished Name (DN).

Use-after-free vulnerability in the _gnutls_handshake_hash_buffers_clear function in lib/gnutls_handshake.c in libgnutls in GnuTLS 2.3.5 through 2.4.0 allows remote attackers to cause a denial of service (crash) or possibly execute arbitrary code via TLS transmission of data that is improperly used when the peer calls gnutls_handshake within a normal session, leading to attempted access to a deallocated libgcrypt handle.

The _gnutls_server_name_recv_params function in lib/ext_server_name.c in libgnutls in gnutls-serv in GnuTLS before 2.2.4 does not properly calculate the number of Server Names in a TLS 1.0 Client Hello message during extension handling, which allows remote attackers to cause a denial of service (crash) or possibly execute arbitrary code via a zero value for the length of Server Names, which leads to a buffer overflow in session resumption data in the pack_security_parameters function, aka GNUTLS-SA-2008-1-1.

Integer signedness error in the _gnutls_ciphertext2compressed function in lib/gnutls_cipher.c in libgnutls in GnuTLS before 2.2.4 allows remote attackers to cause a denial of service (buffer over-read and crash) via a certain integer value in the Random field in an encrypted Client Hello message within a TLS record with an invalid Record Length, which leads to an invalid cipher padding length, aka GNUTLS-SA-2008-1-3.

The _gnutls_recv_client_kx_message function in lib/gnutls_kx.c in libgnutls in gnutls-serv in GnuTLS before 2.2.4 continues to process Client Hello messages within a TLS message after one has already been processed, which allows remote attackers to cause a denial of service (NULL dereference and crash) via a TLS message containing multiple Client Hello messages, aka GNUTLS-SA-2008-1-2.

verify.c in GnuTLS before 1.4.4, when using an RSA key with exponent 3, does not properly handle excess data in the digestAlgorithm.parameters field when generating a hash, which allows remote attackers to forge a PKCS #1 v1.5 signature that is signed by that RSA key and prevents GnuTLS from correctly verifying X.509 and other certificates that use PKCS, a variant of CVE-2006-4339.

The "record packet parsing" in GnuTLS 1.2 before 1.2.3 and 1.0 before 1.0.25 allows remote attackers to cause a denial of service, possibly related to padding bytes in gnutils_cipher.c.

X.509 Certificate Signature Verification in Gnu transport layer security library (GnuTLS) 1.0.16 allows remote attackers to cause a denial of service (CPU consumption) via certificates containing long chains and signed with large RSA keys.