This issue can affect BIND 9 resolvers with `stale-answer-enable yes;` that also make use of the option `stale-answer-client-timeout`, configured with a value greater than zero. If the resolver receives many queries that require recursion, there will be a corresponding increase in the number of clients that are waiting for recursion to complete. If there are sufficient clients already waiting when a new client query is received so that it is necessary to SERVFAIL the longest waiting client (see BIND 9 ARM `recursive-clients` limit and soft quota), then it is possible for a race to occur between providing a stale answer to this older client and sending an early timeout SERVFAIL, which may cause an assertion failure. This issue affects BIND 9 versions 9.16.12 through 9.16.36, 9.18.0 through 9.18.10, 9.19.0 through 9.19.8, and 9.16.12-S1 through 9.16.36-S1.
2023-01-26T21:16:03.273
2025-03-31T14:15:16.573
Modified
CVSSv3.1: 7.5 (HIGH)
| Type | Vendor | Product | Version/Range | Vulnerable? |
|---|---|---|---|---|
| Application | isc | bind | < 9.16.37 | Yes |
| Application | isc | bind | < 9.18.11 | Yes |
| Application | isc | bind | < 9.19.9 | Yes |
| Application | isc | bind | 9.16.12 | Yes |
| Application | isc | bind | 9.16.13 | Yes |
| Application | isc | bind | 9.16.14 | Yes |
| Application | isc | bind | 9.16.21 | Yes |
| Application | isc | bind | 9.16.32 | Yes |
| Application | isc | bind | 9.16.36 | Yes |