Out-of-bound read in mtr

mtr is vulnerable to Out-of-bound read vulnerability in ipinfo_lookup() function. An attacker who can influence the TXT response used for AS lookups can trigger this bug by returning a DNS response that is larger than 512 bytes and uses a crafted compression pointer in the answer NAME field. ipinfo_lookup() function uses the length of the response as the end-of-message boundary for dn_expand() function. The result is a reliable crash. This issue exists in the mtr through version 0.96 and it was fixed in commit 48e1794414d338ce47abc0f27c25ade8788af9c3.