Vulnerability · Published May 21, 2025 · Assigned by isc
CVE-2025-40775DNS message with invalid TSIG causes an assertion failure
High 7.5
In plain English
A high-severity security flaw in BIND 9 from ISC. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 15.3% (higher than 97% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code. Fixed versions are available - upgrade the affected package.
Official 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 packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.20 | bind | 9.18.37-r0 | ALPINE-CVE-2025-40775 |
| Alpine:v3.21 | bind | 9.18.37-r0 | ALPINE-CVE-2025-40775 |
| Alpine:v3.22 | bind | 9.20.9-r0 | ALPINE-CVE-2025-40775 |
| Alpine:v3.23 | bind | 9.20.9-r0 | ALPINE-CVE-2025-40775 |
| Alpine:v3.24 | bind | 9.20.9-r0 | ALPINE-CVE-2025-40775 |
| Debian:13 | bind9 | 1:9.20.9-1 | DEBIAN-CVE-2025-40775 |
| Debian:14 | bind9 | 1:9.20.9-1 | DEBIAN-CVE-2025-40775 |
Affected products (as reported)
Weakness: CWE-232 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H