A flaw in the GnuTLS library is related to shortcomings in handling exceptional states when analyzing the `cert list size` parameter in the `gnutls x509 trust list verify crt2()` function. This issue can be exploited by an attacker to cause a denial of service by passing a specially crafted certificate chain in PEM encoding to `certtool`. The vulnerability can also be triggered when verifying a specially crafted .pem bundle using the "certtool --verify-chain" command, potentially leading to an application crash. Remote attacks are possible, but no exploit has been reported yet.