Arch Linux Security Advisory ASA-202005-13 ========================================== Severity: High Date : 2020-05-20 CVE-ID : CVE-2020-8616 CVE-2020-8617 Package : bind Type : denial of service Remote : Yes Link : https://security.archlinux.org/AVG-1165 Summary ======= The package bind before version 9.16.3-1 is vulnerable to denial of service. Resolution ========== Upgrade to 9.16.3-1. # pacman -Syu "bind>=9.16.3-1" The problems have been fixed upstream in version 9.16.3. Workaround ========== None. Description =========== - CVE-2020-8616 (denial of service) An issue has been found in bind before 9.16.3, which does not sufficiently limit the number of fetches which may be performed while processing a referral response. A malicious actor who intentionally exploits this lack of effective limitation on the number of fetches performed when processing referrals can, through the use of specially crafted referrals, cause a recursing server to issue a very large number of fetches in an attempt to process the referral. This has at least two potential effects: the performance of the recursing server can potentially be degraded by the additional work required to perform these fetches, and the attacker can exploit this behavior to use the recursing server as a reflector in a reflection attack with a high amplification factor. - CVE-2020-8617 (denial of service) An error in bind before 9.16.3 in the code which checks the validity of messages containing TSIG resource records can be exploited by an attacker to trigger an assertion failure in tsig.c, resulting in denial of service to clients. Impact ====== A remote attacker can use the recursor has an amplification vector to cause a denial of service via a crafted reply. In addition, a remote attacker can crash the application by guessing the TSIG key name. References ========== https://kb.isc.org/docs/cve-2020-8616 https://kb.isc.org/docs/cve-2020-8617 https://kb.isc.org/docs/cve-2020-8617-faq-and-supplemental-information http://www.nxnsattack.com/ https://security.archlinux.org/CVE-2020-8616 https://security.archlinux.org/CVE-2020-8617