Bug 1767955 (CVE-2019-16866) - CVE-2019-16866 unbound: uninitialized memory accesses leads to crash via a crafted NOTIFY query
Summary: CVE-2019-16866 unbound: uninitialized memory accesses leads to crash via a cr...
Alias: CVE-2019-16866
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
Depends On: 1779501
Blocks: 1767957
TreeView+ depends on / blocked
Reported: 2019-11-01 17:55 UTC by Guilherme de Almeida Suckevicz
Modified: 2021-10-25 22:12 UTC (History)
2 users (show)

Fixed In Version: unbound 1.9.4
Doc Type: If docs needed, set a value
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Clone Of:
Last Closed: 2021-10-25 22:12:06 UTC

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Description Guilherme de Almeida Suckevicz 2019-11-01 17:55:14 UTC
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.


Comment 2 Huzaifa S. Sidhpurwala 2019-12-04 05:27:14 UTC

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.

Comment 3 Huzaifa S. Sidhpurwala 2019-12-04 05:27:17 UTC
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