Description
When an incoming DNS protocol message includes a Transaction Signature (TSIG), BIND always checks it. If the TSIG contains an invalid value in the algorithm field, BIND immediately aborts with an assertion failure.
This issue affects BIND 9 versions 9.20.0 through 9.20.8 and 9.21.0 through 9.21.7.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| ISC | BIND 9 | 9.20.0 – ≤ 9.20.8, 9.21.0 – ≤ 9.21.7 | — |
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 | 1:9.20.9-1 | — |
| Debian 13 | bind9 | 1:9.20.9-1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 25.04 | bind9 | 1:9.20.4-3ubuntu1.1 | USN-7526-1 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP7 | bind | 9.20.9-150700.3.3.1 | SUSE-SU-2025:01787-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | bind | 9.20.9-1.1 | openSUSE-SU-2025:15156-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | bind | 9.20.9-r0 | — |
| Alpine v3.23 | bind | 9.20.9-r0 | — |
| Alpine v3.22 | bind | 9.20.9-r0 | — |
| Alpine v3.21 | bind | 9.18.37-r0 | — |
| Alpine v3.20 | bind | 9.18.37-r0 | — |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | bind | 9.18.37-r0 | — |
| Alpine v3.18 | bind | 9.18.37-r0 | — |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | bind | 9.20.9-1 | — |
Public exploits
Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.
GitHub 1 repository
-
AlexSvobo/nhi-zero-trust-bypass ★ 6 · May 23, 2025
Demonstrates a real-world zero-trust bypass by exploiting BIND CVE-2025-40775 to disrupt DNS, break secret rotation, and expose static credentials in a cloud-native lab.
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.
Advisories 4
- openSUSE-SU-2025:15156-1 bind-9.20.9-1.1 on GA media SUSE / openSUSE Security Updates · Mar 23, 2026
- USN-7526-1 bind9 vulnerability Ubuntu Security Notices (USN) · Oct 13, 2025
- WID-SEC-2025-1120 Internet Systems Consortium BIND: Schwachstelle ermöglicht Denial of Service BSI CERT-Bund (WID) · Jun 1, 2025
- SUSE-SU-2025:01787-1 Security update for bind SUSE / openSUSE Security Updates · May 31, 2025
References
- CVE-2025-40775 vendor-advisory