Off-by-one error in 'harden-below-nxdomain' logic can shadow a stub/forward zone by a legitimate parent's NXDOMAIN
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||
|---|---|---|---|---|---|---|---|---|---|
| NLnet Labs | Unbound | unaffected |
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No data.
| Vendor | Product | Versions | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Nlnetlabs | Unbound |
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Vendor Solution
This issue is fixed starting with version 1.25.2
| Source | ID | Title |
|---|---|---|
Debian DSA |
DSA-6507-1 | unbound security update |
No CVSS v4.0
No CVSS v3.0
No CVSS v2
This CVE is not in the KEV list.
Exploit prediction score: < 1% (0.218% probability within 30 days)
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Nlnetlabs
Nlnetlabs unbound |
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| Vendors & Products |
Nlnetlabs
Nlnetlabs unbound |
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
ssvc
|
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In NLnet Labs Unbound 1.13.2 up to and including 1.25.1, stub or forward zones where the name is below an intermediate labed below a DNSSEC signed zone could be shadowed by the intermediate label's secure NXDOMAIN answer from the parent. This is caused by an off-by-one error in 'harden-below-nxdomain' logic; enabled by default. It effectively bypasses the configuration and the configured stub/forward zone is never contacted. 'harden-below-nxdomain' does an upward DNS cache walk together with a delegation point guard that does not allow NXDOMAIN synthesis above stub/forward zones. The guard tests the domain name but before stripping a label. This results in an iteration where the domain name equals the configured stub/forward zone apex that passes the guard, strips one more label, and probes the cache at the apex's immediate public parent. If that parent has a cached DNSSEC-secure NXDOMAIN, which it will for any private namespace nested two or more labels under a signed public name, the walk returns it and the configured stub/forward upstream is never contacted. This can only be triggered by the query for the intermediate label (between the stub/forward apex and the DNSSEC parent zone). | |
| Title | Off-by-one error in 'harden-below-nxdomain' logic can shadow a stub/forward zone by a legitimate parent's NXDOMAIN | |
| Weaknesses | CWE-193 | |
| References |
| |
| Metrics |
cvssV3_1
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