In MIT Kerberos 5 (aka krb5) before 1.21.3, an attacker can cause invalid memory reads during GSS message token handling by sending message tokens with invalid length fields.

In MIT Kerberos 5 (aka krb5) before 1.21.3, an attacker can modify the plaintext Extra Count field of a confidential GSS krb5 wrap token, causing the unwrapped token to appear truncated to the application.

Kerberos 5 (aka krb5) 1.21.2 contains a memory leak vulnerability in /krb5/src/kdc/ndr.c.

kdc/do_tgs_req.c in MIT Kerberos 5 (aka krb5) 1.21 before 1.21.2 has a double free that is reachable if an authenticated user can trigger an authorization-data handling failure. Incorrect data is copied from one ticket to another.

lib/kadm5/kadm_rpc_xdr.c in MIT Kerberos 5 (aka krb5) before 1.20.2 and 1.21.x before 1.21.1 frees an uninitialized pointer. A remote authenticated user can trigger a kadmind crash. This occurs because _xdr_kadm5_principal_ent_rec does not validate the relationship between n_key_data and the key_data array count.

PAC parsing in MIT Kerberos 5 (aka krb5) before 1.19.4 and 1.20.x before 1.20.1 has integer overflows that may lead to remote code execution (in KDC, kadmind, or a GSS or Kerberos application server) on 32-bit platforms (which have a resultant heap-based buffer overflow), and cause a denial of service on other platforms. This occurs in krb5_pac_parse in lib/krb5/krb/pac.c. Heimdal before 7.7.1 has "a similar bug."

telnetd in GNU Inetutils through 2.3, MIT krb5-appl through 1.0.3, and derivative works has a NULL pointer dereference via 0xff 0xf7 or 0xff 0xf8. In a typical installation, the telnetd application would crash but the telnet service would remain available through inetd. However, if the telnetd application has many crashes within a short time interval, the telnet service would become unavailable after inetd logs a "telnet/tcp server failing (looping), service terminated" error. NOTE: MIT krb5-appl is not supported upstream but is shipped by a few Linux distributions. The affected code was removed from the supported MIT Kerberos 5 (aka krb5) product many years ago, at version 1.8.

The Key Distribution Center (KDC) in MIT Kerberos 5 (aka krb5) before 1.18.5 and 1.19.x before 1.19.3 has a NULL pointer dereference in kdc/do_tgs_req.c via a FAST inner body that lacks a server field.

ec_verify in kdc/kdc_preauth_ec.c in the Key Distribution Center (KDC) in MIT Kerberos 5 (aka krb5) before 1.18.4 and 1.19.x before 1.19.2 allows remote attackers to cause a NULL pointer dereference and daemon crash. This occurs because a return value is not properly managed in a certain situation.

MIT Kerberos 5 (aka krb5) before 1.17.2 and 1.18.x before 1.18.3 allows unbounded recursion via an ASN.1-encoded Kerberos message because the lib/krb5/asn.1/asn1_encode.c support for BER indefinite lengths lacks a recursion limit.