ALPINE-CVE-2026-50046
In NLnet Labs Unbound 1.15.0 up to and including 1.25.1, the TLS server name used for DNS-over-TLS (DoT) forwarded queries is tied to a struct's ('serviced_query') lifetime but also referenced by another struct ('waiting_tcp'). When the owning struct is jostled out of the mesh while the DoT TCP stream is still handshaking it frees the storage behind the referenced string and if the TLS stream then errors out, it dereferences the freed pointer. The dereference is read-only and the practical impact is a daemon crash resulting in denial of service. A malicious actor that knows a DoT forwarding/stub Unbound's configuration could exploit the vulnerability by quering records in the appropriate zone while keeping Unbound uder pressure so that the jostle logic kicks in. If answers for the vulnerable zone are slow, the likelihood of jostling such queries is higher, although the timing of the jostle needs to be precise. Requirements for a vulnerable Unbound is the existence of a stub/forward zone configured for DoT together with a configured '#authname' suffix on the server identification. The connectivity to the server needs to exhibit a transient failure at the correct time in order to kick off the vulnerable error path.
ALPINE-CVE-2026-50046
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-2026-50046
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": "1.15.0"
},
{
"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-2026-50046.json"
},
"ecosystem_specific": {}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "1.15.0"
},
{
"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-2026-50046.json"
},
"ecosystem_specific": {}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "1.15.0"
},
{
"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-2026-50046.json"
},
"ecosystem_specific": {}
}
]Publisher severity
No explicit severity was provided.
- Event
- #54490 · Revision 1
- Added to Heist Feed
- Publisher date