Description
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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| ISC | BIND 9 | 9.16.12 – ≤ 9.16.36, 9.18.0 – ≤ 9.18.10, 9.19.0 – ≤ 9.19.8, 9.16.12-S1 – ≤ 9.16.36-S1 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | bind9 | 1:9.18.11-1 | — |
| Debian 13 | bind9 | 1:9.18.11-1 | — |
| Debian 12 | bind9 | 1:9.18.11-1 | — |
| Debian 11 | bind9 | 1:9.16.37-1~deb11u1 | DSA-5329-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 22.04 LTS | bind9 | 1:9.18.1-1ubuntu1.3 | USN-5827-1 |
| Ubuntu 20.04 LTS | bind9 | 1:9.16.1-0ubuntu2.12 | USN-5827-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 9 | bind +9 | 32:9.16.23-11.el9 | RHSA-2023:2261 |
| RHEL 8 | bind9.16 +8 | 32:9.16.23-0.14.el8 | RHSA-2023:2792 |
AlmaLinux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux 9 | bind +9 | 32:9.16.23-11.el9 | ALSA-2023:2261 |
| AlmaLinux 8 | bind9.16 +8 | 32:9.16.23-0.14.el8 | ALSA-2023:2792 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP4 | bind | 9.16.37-150400.5.17.1 | SUSE-SU-2023:0341-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | bind | 9.18.11-1.1 | openSUSE-SU-2024:12641-1 |
| openSUSE Leap 15.4 | bind | 9.16.37-150400.5.17.1 | SUSE-SU-2023:0341-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | bind | 9.18.11-r0 | — |
| Alpine v3.23 | bind | 9.18.11-r0 | — |
| Alpine v3.22 | bind | 9.18.11-r0 | — |
| Alpine v3.21 | bind | 9.18.11-r0 | — |
| Alpine v3.20 | bind | 9.18.11-r0 | — |
Show 6 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | bind | 9.18.11-r0 | — |
| Alpine v3.18 | bind | 9.18.11-r0 | — |
| Alpine v3.17 | bind | 9.18.11-r0 | — |
| Alpine v3.16 | bind | 9.16.37-r0 | — |
| Alpine v3.15 | bind | 9.16.37-r0 | — |
| Alpine v3.14 | bind | 9.16.37-r0 | — |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2023 | bind +16 | 32:9.16.38-1.amzn2023 | ALAS2023-2023-161 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 2 (CBL-Mariner) | bind | 9.16.37-2 | — |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 9 | bind +9 | 32:9.16.23-11.el9 | ELSA-2023-2261 |
| Oracle Linux 8 | bind9.16 +8 | 32:9.16.23-0.14.el8 | ELSA-2023-2792 |
Wolfi
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Wolfi rolling | bind | 9.18.11-r0 | — |
Advisories 15
- ALSA-2023:2261 Moderate: bind security and bug fix update AlmaLinux Security Advisories · Oct 29, 2026
- ALSA-2023:2792 Moderate: bind9.16 security and bug fix update AlmaLinux Security Advisories · Oct 29, 2026
- RHSA-2023:2792 Red Hat Security Advisory: bind9.16 security and bug fix update Red Hat Security Advisories (RHSA) · Sep 2, 2026
- RHSA-2023:2261 Red Hat Security Advisory: bind security and bug fix update Red Hat Security Advisories (RHSA) · Sep 2, 2026
- WID-SEC-2023-0207 Internet Systems Consortium BIND: Mehrere Schwachstellen ermöglichen Denial of Service BSI CERT-Bund (WID) · Aug 6, 2026
- WID-SEC-2023-2917 Xerox FreeFlow Print Server: Mehrere Schwachstellen BSI CERT-Bund (WID) · Jun 30, 2026
- USN-5827-1 bind9 vulnerabilities Ubuntu Security Notices (USN) · Apr 22, 2026
- DSA-5329-1 bind9 - security update Debian Security (DSA / DLA) · Mar 9, 2026
- SUSE-SU-2023:0341-1 Security update for bind SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2024:12641-1 bind-9.18.11-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- WID-SEC-2023-1542 Red Hat OpenShift: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 18, 2025
- WID-SEC-2023-1424 Xerox FreeFlow Print Server für Solaris: Mehrere Schwachstellen BSI CERT-Bund (WID) · Oct 6, 2025
- ELSA-2023-2792 Moderate: bind9.16 security and bug fix update (Oracle Linux 8) Oracle Linux Security Advisories (ELSA) · May 24, 2023
- ELSA-2023-2261 Moderate: bind security and bug fix update (Oracle Linux 9) Oracle Linux Security Advisories (ELSA) · May 15, 2023
- ALAS2023-2023-161 Important: bind security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Apr 19, 2023
References
- CVE-2022-3924 vendor-advisory