A possible assertion failure when 'stale-answer-client-timeout' is set to '0'
CVE-2025-40777 is fixed in 20 products on 1 platform, first by bind9 1:9.20.4-3ubuntu1.2, released July 16, 2025. It is not reported as exploited. Patch Radar priority: High.
If a `named` caching resolver is configured with `serve-stale-enable``yes`, and with `stale-answer-client-timeout` set to `0` (the onlyallowable value other than `disabled`), and if the resolver, in the processof resolving a query, encounters a CNAME chain involving a specificcombination of cached or authoritative records, the daemon will abort withan assertion failure.This issue affects BIND 9 versions 9.20.0 through 9.20.10, 9.21.0 through9.21.9, and 9.20.9-S1 through 9.20.10-S1.
Where it's fixed
| Product | Fixed in | Fix | Released |
|---|---|---|---|
| Linux | |||
| bind · amzn 2023 | 32:9.18.33-1.amzn2023.0.3 | ALAS2023-2025-1105 | Jul 21, 2025 |
| bind · sles 15.7 | 9.20.11-150700.3.6.1 | SUSE-SU-2025:02349-1 | Jul 17, 2025 |
| bind-chroot · amzn 2023 | 32:9.18.33-1.amzn2023.0.3 | ALAS2023-2025-1105 | Jul 21, 2025 |
| bind-debuginfo · amzn 2023 | 32:9.18.33-1.amzn2023.0.3 | ALAS2023-2025-1105 | Jul 21, 2025 |
| bind-debugsource · amzn 2023 | 32:9.18.33-1.amzn2023.0.3 | ALAS2023-2025-1105 | Jul 21, 2025 |
| bind-devel · amzn 2023 | 32:9.18.33-1.amzn2023.0.3 | ALAS2023-2025-1105 | Jul 21, 2025 |
| bind-dnssec-utils · amzn 2023 | 32:9.18.33-1.amzn2023.0.3 | ALAS2023-2025-1105 | Jul 21, 2025 |
| bind-dnssec-utils-debuginfo · amzn 2023 | 32:9.18.33-1.amzn2023.0.3 | ALAS2023-2025-1105 | Jul 21, 2025 |
| bind-doc · amzn 2023 | 32:9.18.33-1.amzn2023.0.3 | ALAS2023-2025-1105 | Jul 21, 2025 |
| bind-libs · amzn 2023 | 32:9.18.33-1.amzn2023.0.3 | ALAS2023-2025-1105 | Jul 21, 2025 |
| bind-libs-debuginfo · amzn 2023 | 32:9.18.33-1.amzn2023.0.3 | ALAS2023-2025-1105 | Jul 21, 2025 |
| bind-license · amzn 2023 | 32:9.18.33-1.amzn2023.0.3 | ALAS2023-2025-1105 | Jul 21, 2025 |
| bind-utils · amzn 2023 | 32:9.18.33-1.amzn2023.0.3 | ALAS2023-2025-1105 | Jul 21, 2025 |
| bind-utils-debuginfo · amzn 2023 | 32:9.18.33-1.amzn2023.0.3 | ALAS2023-2025-1105 | Jul 21, 2025 |
| bind9 · Debian 13.5 (trixie) | 1:9.20.11-1 | DEBIAN-CVE-2025-40777 | Jul 16, 2025 |
| bind9 · Debian 14 | 1:9.20.11-1 | DEBIAN-CVE-2025-40777 | Jul 16, 2025 |
| bind9 · Ubuntu 25.04 (plucky) | 1:9.20.4-3ubuntu1.2 | bind9 1:9.20.4-3ubuntu1.2 | Jul 16, 2025 |
| bind9-dnsutils · Ubuntu 25.04 (plucky) | 1:9.20.4-3ubuntu1.2 | bind9-dnsutils 1:9.20.4-3ubuntu1.2 | Jul 16, 2025 |
| bind9-host · Ubuntu 25.04 (plucky) | 1:9.20.4-3ubuntu1.2 | bind9-host 1:9.20.4-3ubuntu1.2 | Jul 16, 2025 |
| bind9-libs · Ubuntu 25.04 (plucky) | 1:9.20.4-3ubuntu1.2 | bind9-libs 1:9.20.4-3ubuntu1.2 | Jul 16, 2025 |
| bind9-utils · Ubuntu 25.04 (plucky) | 1:9.20.4-3ubuntu1.2 | bind9-utils 1:9.20.4-3ubuntu1.2 | Jul 16, 2025 |
| bind9utils · Ubuntu 25.04 (plucky) | 1:9.20.4-3ubuntu1.2 | bind9utils 1:9.20.4-3ubuntu1.2 | Jul 16, 2025 |
| dnsutils · Ubuntu 25.04 (plucky) | 1:9.20.4-3ubuntu1.2 | dnsutils 1:9.20.4-3ubuntu1.2 | Jul 16, 2025 |
Patch Radar data is free to use with attribution. Terms and how to credit it.
Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.