What’s Vulnerable › Vulnerabilities

CVE-2020-8622: A truncated TSIG response can lead to an assertion failure

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 5.8% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2020-08-21 · updated 2026-06-17
• Weakness: CWE-617

Description

In BIND 9.0.0 -> 9.11.21, 9.12.0 -> 9.16.5, 9.17.0 -> 9.17.3, also affects 9.9.3-S1 -> 9.11.21-S1 of the BIND 9 Supported Preview Edition, An attacker on the network path for a TSIG-signed request, or operating the server receiving the TSIG-signed request, could send a truncated response to that request, triggering an assertion failure, causing the server to exit. Alternately, an off-path attacker would have to correctly guess when a TSIG-signed request was sent, along with other characteristics of the packet and message, and spoof a truncated response to trigger an assertion failure, causing the server to exit.

Affected products

• Canonical Ubuntu Linux: 12.04, 14.04, 16.04, 18.04, 20.04
• Debian Linux: 9.0, 10.0
• Fedoraproject Fedora: 31, 32
• ISC BIND: from 9.0.0 through 9.11.21; from 9.12.0 through 9.16.5; from 9.17.0 through 9.17.3; 9.9.3-s1, 9.11.21-s1
• NetApp Steelstore Cloud Integrated Storage: all versions
• openSUSE Leap: 15.1, 15.2
• Oracle Corporation Communications Diameter Signaling Router (DSR): from 8.0.0 through 8.5.0
• Synology DNS Server: before 2.2.2-5028 — fixed in 2.2.2-5028

How to fix

Upgrade to a fixed version: Synology DNS Server 2.2.2-5028. Check the vendor advisory for mitigations.

References

• http://lists.opensuse.org/opensuse-security-announce/2020-10/msg00041.html
• http://lists.opensuse.org/opensuse-security-announce/2020-10/msg00044.html
• https://kb.isc.org/docs/cve-2020-8622
• https://lists.debian.org/debian-lts-announce/2020/08/msg00053.html
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/DQN62GBMCIC5AY4KYADGXNKVY6AJKSJE/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZKAMJZXR66P6S5LEU4SN7USSNCWTXEXP/
• https://security.gentoo.org/glsa/202008-19
• https://security.netapp.com/advisory/ntap-20200827-0003/
• https://usn.ubuntu.com/4468-1/
• https://usn.ubuntu.com/4468-2/
• https://www.debian.org/security/2020/dsa-4752
• https://www.oracle.com/security-alerts/cpuoct2021.html

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