What’s Vulnerable › Vulnerabilities

CVE-2019-16866

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 3.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2019-10-03 · updated 2026-10-08
• Weakness: CWE-755

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.

Affected products

• Canonical Ubuntu Linux: 19.04
• NLnet Labs Unbound: before 1.9.4 — fixed in 1.9.4

How to fix

Upgrade to a fixed version: NLnet Labs Unbound 1.9.4. Check the vendor advisory for mitigations.

References

• https://github.com/NLnetLabs/unbound/blob/release-1.9.4/doc/Changelog
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/E65NCWZZB2D75ZIYWPXKMVGSGNYW4JMC/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MLRHE7TQFAOV4MB2ELTOGESZYUL65NUJ/
• https://nlnetlabs.nl/downloads/unbound/CVE-2019-16866.txt
• https://seclists.org/bugtraq/2019/Oct/23
• https://usn.ubuntu.com/4149-1/
• https://www.debian.org/security/2019/dsa-4544
• https://github.com/NLnetLabs/unbound/blob/release-1.9.4/doc/Changelog
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/E65NCWZZB2D75ZIYWPXKMVGSGNYW4JMC/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/MLRHE7TQFAOV4MB2ELTOGESZYUL65NUJ/
• https://nlnetlabs.nl/downloads/unbound/CVE-2019-16866.txt
• https://seclists.org/bugtraq/2019/Oct/23

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