CVE-2020-8617
A logic error in code which checks TSIG validity can be used to trigger an assertion failure in tsig.c
- Published
- May 19, 2020
- Updated
- Sep 16, 2024
- Assigning CNA
- isc
- Evidence observed
- May 20, 2020
Primary CVSS
nvd · CVSS 3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HHigh · next 30 days
- Percentile
- 99.8%
- Model date
- Sep 21, 2026
EPSS is a statistical estimate, not a certainty or a measure of impact. Combine it with CVSS, KEV status, exposure and your environment.
Summary
Using a specially-crafted message, an attacker may potentially cause a BIND server to reach an inconsistent state if the attacker knows (or successfully guesses) the name of a TSIG key used by the server. Since BIND, by default, configures a local session key even on servers whose configuration does not otherwise make use of it, almost all current BIND servers are vulnerable. In releases of BIND dating from March 2018 and after, an assertion check in tsig.c detects this inconsistent state and deliberately exits. Prior to the introduction of the check the server would continue operating in an inconsistent state, with potentially harmful results.
Sources
3Proof-of-concept exploit for CVE-2020-8617 targeting BIND DNS servers via TKEY transaction abuse, with Docker-based lab environment for testing.
Proof-of-concept exploit for CVE-2020-8617, demonstrating the vulnerability and enabling security testing and validation.
Responsible use
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