BIND 9.18.48 Crash upon Serve Stale Enabling, with general: critical: exiting (due to assertion failure) and Recursion Loop Detected

[Ibrahim Almahfooz]

We tried 9.18.48 (latest of 9.18.x) also crashed with the same error within
a couple of minutes. We will perform another upgrade to version 9.20.22 and
see what happens.

Is the "recursion loop detected" message in the logs considered normal when
stale serve is enabled? or is it happening due to misconfiguration?

Best regards


On Sun, 3 May 2026 at 10:54, Ondřej Surý <ondrej at isc.org> wrote:

> You are running outdated version - BIND 9.18.41, first step would be to
> upgrade to latest 9.18 version or even better to latest 9.20 as BIND 9.18
> will reach end of life quite soon.
>
> Ondrej
> --
> Ondřej Surý (He/Him)
> ondrej at isc.org
>
> ADHD brain at work: I sometimes lose track of my inbox. Please feel free
> to send a gentle nudge if you're waiting on a reply!
>
> My working hours and your working hours may be different. Please do not
> feel obligated to reply outside your normal working hours.
>
> On 3. 5. 2026, at 9:40, Ibrahim Almahfooz <ibrahim.nezar at sevennet.net>
> wrote:
>
> 
> Hi,
>
> Recently we have enabled stale serve on our recursive BIND 9.18.41
> (Extended Support Version), the service crashes after a few minutes,
> showing the following lines inside the log files:
>
> *Sample from named.run logs showing the recursion loop:
> 03-May-2026 07:37:41.553 client: info: client @0x7f32d0d4c498
> 10.40.153.193#14013 (api.al-array.com): view our-users: recursion loop
> detected
> 03-May-2026 07:37:41.553 client: info: client @0x7f32d0993c98
> 10.36.16.177#10683 (api.al-array.com): view our-users: recursion loop
> detected
> 03-May-2026 07:37:41.702 client: info: client @0x7f32d0da7098
> 10.36.24.213#47838 (ninja12002.serv00.net): view our-users: recursion
> loop detected
> 03-May-2026 07:37:41.717 client: info: client @0x7f32d25e4098
> 10.48.72.221#37292 (hayward.walsivrtgam.net): view our-users: recursion
> loop detected
>
> *Sample from default logs showing the assertion failure:
> default.1:03-May-2026 07:38:30.213 general: critical:
> /opt/isc/isc-bind/root/usr/lib64/libisc-9.18.41.so(isc_assertion_failed+0xe)
> [0x7f32d615538e]
> default.1:03-May-2026 07:38:30.213 general: critical: exiting (due to
> assertion failure)
>
> *Our resolver is receiving around 20k QPS.
>
> *Below is the configuration
> ## Global Named Configuration
> options {
>         directory "/var/opt/isc/scls/isc-bind/named/data";
>         listen-on { 127.0.0.1; 192.168.20.2; };
>         allow-transfer {"none";};
>         dnssec-validation auto;
>         querylog no;
>         recursive-clients 10000;
>         dnstap {all;};
>         dnstap-output file "named-logs/dnstap.file";
>         dnstap-identity "ns02.ourdomain.net";
>         deny-answer-addresses { deny-answer-referral-acl; };
> };
>
> # For monitoring systems to fetch named statistics
> statistics-channels {
>   inet 192.168.20.2 port 8080 allow {192.168.10.0/24;};
>   inet 127.0.0.1 port 8083 allow { any; };
> };
>
> # Logging module
> include "/etc/opt/isc/scls/isc-bind/logging.conf";
>
>
> #### Clients ACLs ####
>
> acl deny-answer-referral-acl {
>         127.0.0.1/32;
>         192.168.20.2/32;
> };
>
> acl our-users-acl {
>         127.0.0.1;
>         192.168.0.0/16;
> };
>
> #### Users ####
> view "our-users" {
>         match-clients { our-users-acl; };
>         allow-query { our-users-acl; };
>         recursion yes;
>         stale-answer-enable yes;
>         stale-cache-enable yes;
>         max-stale-ttl 12H;
>         stale-answer-ttl 30s;
>         stale-refresh-time 30s;
>         stale-answer-client-timeout 0;
>
> zone "ourdomain.net" {
>         type master;
>         file "zones/ourdomain.net";
>         zone-statistics yes;
>         };
>
> zone "." IN {
>         type hint;
>         file "named.root";
>         };
> };
>
> #### END OF NAMED CONFIGURATIONS
>
>
> Appreciate the support
>
> Thank you
>
>
> --
> Visit https://lists.isc.org/mailman/listinfo/bind-users to unsubscribe
> from this list.
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.isc.org/pipermail/bind-users/attachments/20260503/3aefe559/attachment.htm>