ALPINE-CVE-2026-44687
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).
ALPINE-CVE-2026-44687
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: osv:ALPINE-CVE-2026-44687
unbound
Source reference: /affected/0/package/name
- Affected versions
- Not stated in this record
- Fixed versions
- 1.25.2-r0
Source reference:
/affected/0/ranges - Prerequisites
- Not stated in this record
unbound
Source reference: /affected/1/package/name
- Affected versions
- Not stated in this record
- Fixed versions
- 1.25.2-r0
Source reference:
/affected/1/ranges - Prerequisites
- Not stated in this record
unbound
Source reference: /affected/2/package/name
- Affected versions
- Not stated in this record
- Fixed versions
- 1.25.2-r0
Source reference:
/affected/2/ranges - Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "1.13.2"
},
{
"fixed": "1.25.2-r0"
}
]
}
],
"package": {
"name": "unbound",
"purl": "pkg:apk/alpine/unbound?arch=source",
"ecosystem": "Alpine:v3.22"
},
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2026-44687.json"
},
"ecosystem_specific": {}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "1.13.2"
},
{
"fixed": "1.25.2-r0"
}
]
}
],
"package": {
"name": "unbound",
"purl": "pkg:apk/alpine/unbound?arch=source",
"ecosystem": "Alpine:v3.23"
},
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2026-44687.json"
},
"ecosystem_specific": {}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "1.13.2"
},
{
"fixed": "1.25.2-r0"
}
]
}
],
"package": {
"name": "unbound",
"purl": "pkg:apk/alpine/unbound?arch=source",
"ecosystem": "Alpine:v3.24"
},
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2026-44687.json"
},
"ecosystem_specific": {}
}
]Publisher severity
No explicit severity was provided.
- Event
- #54432 · Revision 1
- Added to Heist Feed
- Publisher date