The asn1_get_length_der function in decoding.c in GNU Libtasn1 before 2.12, as used in GnuTLS before 3.0.16 and other products, does not properly handle certain large length values, which allows remote attackers to cause a denial of service (heap memory corruption and application crash) or possibly have unspecified other impact via a crafted ASN.1 structure.

Double free vulnerability in libgnutls in GnuTLS before 3.0.14 allows remote attackers to cause a denial of service (application crash) or possibly have unspecified other impact via a crafted certificate list.

The _gnutls_x509_oid2mac_algorithm function in lib/gnutls_algorithms.c in GnuTLS before 1.4.2 allows remote attackers to cause a denial of service (crash) via a crafted X.509 certificate that uses a hash algorithm that is not supported by GnuTLS, which triggers a NULL pointer dereference.

The gnutls_x509_crt_get_serial function in the GnuTLS library before 1.2.1, when running on big-endian, 64-bit platforms, calls the asn1_read_value with a pointer to the wrong data type and the wrong length value, which allows remote attackers to bypass the certificate revocation list (CRL) check and cause a stack-based buffer overflow via a crafted X.509 certificate, related to extraction of a serial number.

libgnutls in GnuTLS before 2.8.2 does not properly handle a '\0' character in a domain name in the subject's (1) Common Name (CN) or (2) Subject Alternative Name (SAN) field of an X.509 certificate, which allows man-in-the-middle attackers to spoof arbitrary SSL servers via a crafted certificate issued by a legitimate Certification Authority.

The Network Security Services (NSS) library before 3.12.3, as used in Firefox; GnuTLS before 2.6.4 and 2.7.4; OpenSSL 0.9.8 through 0.9.8k; and other products support MD2 with X.509 certificates, which might allow remote attackers to spoof certificates by using MD2 design flaws to generate a hash collision in less than brute-force time. NOTE: the scope of this issue is currently limited because the amount of computation required is still large.

gnutls-cli in GnuTLS before 2.6.6 does not verify the activation and expiration times of X.509 certificates, which allows remote attackers to successfully present a certificate that is (1) not yet valid or (2) no longer valid, related to lack of time checks in the _gnutls_x509_verify_certificate function in lib/x509/verify.c in libgnutls_x509, as used by (a) Exim, (b) OpenLDAP, and (c) libsoup.

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.