unbound-1.21.1

[Bruce Dubbs]

New point version.

[Douglas R. Reno]

Marked as elevated due to CVE-2024-8508

[Douglas R. Reno]

Vulnerability information:

Unbounded name compression could lead to Denial of Service
Date:	2024-10-03
CVE:	CVE-2024-8508
Credit:	Toshifumi Sakaguchi
Affects:	Unbound up to and including version 1.21.0
Not affected:	Other versions
Severity:	Medium (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L)
Impact:	Possibility of DoS in orchestrated attacks
Solution:	Download patched version of Unbound, or apply the patch manually

Malicious upstreams responses with very large RRsets can cause Unbound to spend a 
considerable time applying name compression to downstream replies. This can lead to 
degraded performance and eventually denial of service in well orchestrated attacks.

The vulnerability can be exploited by a malicious actor querying Unbound for the 
specially crafted contents of a malicious zone with very large RRsets. Before Unbound 
replies to the query it will try to apply name compression which was an unbounded 
operation that could lock the CPU until the whole packet was complete.

Unbound version 1.21.1 introduces a hard limit on the number of name compression 
calculations it is willing to do per packet. Packets that need more compression will 
result in semi-compressed packets or truncated packets, even on TCP for huge messages, 
to avoid locking the CPU for long.

This change should not affect normal DNS traffic.

Unbound 1.21.1 contains a patch. If you cannot upgrade you can also apply the patch 
manually. To do this, apply the patch on the Unbound source directory with patch -p1 < 
patch_CVE-2024-8508.diff and then run make install to install Unbound.

Release notes:

Bug Fixes

    Fix CVE-2024-8508, unbounded name compression could lead to denial of service.

[Douglas R. Reno]

Fixed at 807a0ba7602a8dfa95ae69855e95aca82103294b

SA-12.2-020 issued