CVE-2019-16866

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Last Modified: UTC

Description

The CVE Program describes this issue as:

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.

Statement

This issue has been classified as having low security impact because: - per default, unbound is not configured to listen on a public interface - per default, the ACL is limited to localhost, so even if listening to a public interface, the crash cannot happen per default It mostly affects people running unbound as a "public" DNS resolver. Using such configurations, unbound has no valuable secrets that could be obtained by a successful attack, so at best the server crashes and restarts, resulting in an empty DNS cache. Sustained sending of packets would result in a DoS though.

This issue has been classified as having low security impact because:

  • per default, unbound is not configured to listen on a public interface
  • per default, the ACL is limited to localhost, so even if listening to a public interface, the crash cannot happen per default

It mostly affects people running unbound as a "public" DNS resolver. Using such configurations, unbound has no valuable secrets that could be obtained by a successful attack, so at best the server crashes and restarts, resulting in an empty DNS cache. Sustained sending of packets would result in a DoS though.

Additional information

  • Bugzilla 1767955: unbound: uninitialized memory accesses leads to crash via a crafted NOTIFY query
  • CWE-822: Untrusted Pointer Dereference
  • FAQ: Frequently asked questions about CVE-2019-16866

Common Vulnerability Scoring System (CVSS) Score Details

Important note

CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).

The following CVSS metrics and score provided are preliminary and subject to review.

CVSS v3 Score Breakdown
Red HatNVD

CVSS v3 Base Score

5.3

7.5

Attack Vector

Network

Network

Attack Complexity

High

Low

Privileges Required

Low

None

User Interaction

None

None

Scope

Unchanged

Unchanged

Confidentiality Impact

None

None

Integrity Impact

None

None

Availability Impact

High

High

CVSS v3 Vector

Red Hat: CVSS:3.0/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Frequently Asked Questions

Why is Red Hat's CVSS v3 score or Impact different from other vendors?

My product is listed as "Under investigation" or "Affected", when will Red Hat release a fix for this vulnerability?

What can I do if my product is listed as "Will not fix"?

What can I do if my product is listed as "Fix deferred"?

What is a mitigation?

I have a Red Hat product but it is not in the above list, is it affected?

Why is my security scanner reporting my product as vulnerable to this vulnerability even though my product version is fixed or not affected?

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