A logic error in code which checks TSIG validity can be used to trigger an assertion failure in tsig.c

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.

Timeline

1. May 19, 2020, 2:05 PM UTCCVE published
2. May 20, 2020Public exploit on Exploit-DB

   EDB-48521

3. Sep 16, 2024, 8:26 PM UTCRecord last updated
4. Oct 28, 2026EPSS reached 10%

   FIRST estimates at least a 10% chance of exploitation in the next 30 days

Affected versions

• ISC BIND9

  Version range not reported

References 16