CVE-2019-16866 — Unbound before 1
Unbound before 1.9.4 accesses uninitialized memory, which allows remote attackers to trigger a crash via a crafted NOTIFY query. The source IP address of the query must match an access-control rule.
Published
2019-10-03T19:15:09.550
Last modified
2026-10-08T21:17:16.327
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
01What is this vulnerability?
Unbound before 1.9.4 accesses uninitialized memory, which allows remote attackers to trigger a crash via a crafted NOTIFY query. The source IP address of the query must match an access-control rule.
02Affected products
No structured affected-product list available — see references below for vendor advisories.
03Active exploitation status
Not currently listed on the CISA Known Exploited Vulnerabilities (KEV) catalog. EPSS is the best forward-looking signal — see the EPSS row above.
04Recommended remediation
- Patch to a fixed version listed in the vendor advisory (see references below).
- Mitigate with WAF rules, network egress filters, or feature flags where the patch is not yet available.
- Hunt historical logs for exploitation indicators — see Detection signatures below.
05Technical details
For the full vendor write-up, exploit chains, and reference implementations, see the references list in section 09.
06Detection signatures
Ask SARA in chat to draft a starting detection for this CVE in your stack of choice.
07Related CVEs
No directly-cited follow-up CVEs in the KB record for this advisory. The references list in section 09 carries the vendor cross-references.
08Timeline
- Published: 2019-10-03T19:15:09.550
- Last modified: 2026-10-08T21:17:16.327
09References
- github.com — https://github.com/NLnetLabs/unbound/blob/release-1.9.4/doc/Changelog
- lists.fedoraproject.org — https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedorapro…
- lists.fedoraproject.org — https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedorapro…
- nlnetlabs.nl — https://nlnetlabs.nl/downloads/unbound/CVE-2019-16866.txt
- seclists.org — https://seclists.org/bugtraq/2019/Oct/23
- usn.ubuntu.com — https://usn.ubuntu.com/4149-1/
- www.debian.org — https://www.debian.org/security/2019/dsa-4544
- github.com — https://github.com/NLnetLabs/unbound/blob/release-1.9.4/doc/Changelog
- lists.fedoraproject.org — https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedorapro…
- lists.fedoraproject.org — https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedorapro…
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