Birthday Attack against Resolvers supporting ECS
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ISC | BIND 9 | unaffected |
|
No data.
No data.
| Vendor | Product | Versions |
|---|---|---|
| Isc | Bind | — |
Vendor Solution
Upgrade to the patched release most closely related to your current version of BIND 9: 9.18.38-S1 or 9.20.11-S1.
Vendor Workaround
Disable ECS in BIND by removing the `ecs-zones` option from `named.conf`.
| Source | ID | Title |
|---|---|---|
EUVD |
EUVD-2025-21705 | A `named` caching resolver that is configured to send ECS (EDNS Client Subnet) options may be vulnerable to a cache-poisoning attack. This issue affects BIND 9 versions 9.11.3-S1 through 9.16.50-S1, 9.18.11-S1 through 9.18.37-S1, and 9.20.9-S1 through 9.20.10-S1. |
No CVSS v4.0
No CVSS v3.0
No CVSS v2
This CVE is not in the KEV list.
Exploit prediction score: < 1% (0.227% probability within 30 days)
| Link | Providers |
|---|---|
| https://kb.isc.org/docs/cve-2025-40776 |
|
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
ssvc
|
| Type | Values Removed | Values Added |
|---|---|---|
| Description | A `named` caching resolver that is configured to send ECS (EDNS Client Subnet) options may be vulnerable to a cache-poisoning attack. This issue affects BIND 9 versions 9.11.3-S1 through 9.16.50-S1, 9.18.11-S1 through 9.18.37-S1, and 9.20.9-S1 through 9.20.10-S1. | |
| Title | Birthday Attack against Resolvers supporting ECS | |
| Weaknesses | CWE-349 | |
| References |
| |
| Metrics |
cvssV3_1
|