BIND 9: Acceptance of Extraneous Untrusted Data With Trusted Data
CVE-2025-40776 is a high-severity acceptance of extraneous untrusted data with trusted data vulnerability in BIND 9 from ISC, with a CVSS 3.1 base score of 8.6 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected BIND 9 versions: 9.11.3-S1 through 9.16.50-S1; 9.18.11-S1 through 9.18.37-S1; 9.20.9-S1 through 9.20.10-S1. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.23% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of BIND 9 you run against the affected versions below, and install the vendor's latest release.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| ISC | BIND 9 | 9.11.3-S1 through 9.16.50-S1; 9.18.11-S1 through 9.18.37-S1; 9.20.9-S1 through 9.20.10-S1 | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- ChangedThe attack can reach beyond the vulnerable component into other systems.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- HighData or code can be modified at will.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N. Scored by CNA (isc.org).
Official 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.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Acceptance of Extraneous Untrusted Data With Trusted Data
The product, when processing trusted data, accepts any untrusted data that is also included with the trusted data, treating the untrusted data as if it were trusted.
More Acceptance of Extraneous Untrusted Data With Trusted Data vulnerabilities (CWE-349)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Other references
Other vulnerabilities in BIND 9
- 7.5 High severity
- 7.5 High severity
- 8.1 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
Recent Acceptance of Extraneous Untrusted Data With Trusted Data vulnerabilities
- 8.7 High severity
- 7.5 High severity
- 7.1 High severity
- 7.2 High severity
- 7.2 High severity
Spotted an error? Tell us.