Fix KDC null deref on TGS inner body null server After the KDC decodes a FAST inner body, it does not check for a null server. Prior to commit 39548a5b17bbda9eeb63625a201cfd19b9de1c5b this would typically result in an error from krb5_unparse_name(), but with the addition of get_local_tgt() it results in a null dereference. Add a null check. Reported by Joseph Sutton of Catalyst. CVE-2021-37750: In MIT krb5 releases 1.14 and later, an authenticated attacker can cause a null dereference in the KDC by sending a FAST TGS request with no server field. (cherry picked from commit d775c95af7606a51bf79547a94fa52ddd1cb7f49) https://github.com/krb5/krb5/commit/f5162aa63fb7652eae2ad74be4c3bdf869c0d1f7 Author: Greg Hudson Commit: f5162aa63fb7652eae2ad74be4c3bdf869c0d1f7 Branch: krb5-1.19 src/kdc/do_tgs_req.c | 5 +++++ 1 files changed, 5 insertions(+), 0 deletions(-)