Unbound before 1.9.4 accesses uninitialized memory, which allows remote attackers to trigger a crash via a crafted NOTIFY query. The…

Description

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.

Scores

EPSS (exploitation in 30 days)

3.5% · top 11% of all CVEs (7 Nov 2026)

CISA SSVC

Exploitation: none · Automatable: yes · Technical impact: partial

The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.5.

Weakness

• n/a
• CWE-755 (opens in a new tab)All about CWE-755 and its CVEs
• CWE-908 (opens in a new tab)All about CWE-908 and its CVEs

Affected products

• n/a

  • affected n/a

References (7)

• https://github.com/NLnetLabs/unbound/blob/release-1.9.4/doc/Changelog (opens in a new tab)x_refsource_MISCx_transferred
• https://nlnetlabs.nl/downloads/unbound/CVE-2019-16866.txt (opens in a new tab)x_refsource_MISCx_transferred
• USN-4149-1 (opens in a new tab)vendor-advisoryx_refsource_UBUNTUx_transferred
• DSA-4544 (opens in a new tab)vendor-advisoryx_refsource_DEBIANx_transferred
• 20191016 [SECURITY] [DSA 4544-1] unbound security update (opens in a new tab)mailing-listx_refsource_BUGTRAQx_transferred
• FEDORA-2019-e99b716a92 (opens in a new tab)vendor-advisoryx_refsource_FEDORAx_transferred
• FEDORA-2019-0418c12a36 (opens in a new tab)vendor-advisoryx_refsource_FEDORAx_transferred

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisories (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2019-16866](https://trackcve.app/badge/CVE-2019-16866.svg)](https://trackcve.app/cve/CVE-2019-16866)

Record last updated 8 Oct 2026, 21:03 UTC.