NLnet Labs Unbound up to and including version 1.21.0 contains a vulnerability when handling replies with very large RRsets that it needs to perform name compression for. 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.
History

Fri, 04 Oct 2024 13:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

threat_severity

Moderate


Thu, 03 Oct 2024 18:30:00 +0000

Type Values Removed Values Added
First Time appeared Nlnetlabs
Nlnetlabs unbound
CPEs cpe:2.3:a:nlnetlabs:unbound:*:*:*:*:*:*:*:*
Vendors & Products Nlnetlabs
Nlnetlabs unbound
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Thu, 03 Oct 2024 16:45:00 +0000

Type Values Removed Values Added
Description NLnet Labs Unbound up to and including version 1.21.0 contains a vulnerability when handling replies with very large RRsets that it needs to perform name compression for. 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.
Title Unbounded name compression could lead to Denial of Service
Weaknesses CWE-606
References
Metrics cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L'}


cve-icon MITRE

Status: PUBLISHED

Assigner: NLnet Labs

Published: 2024-10-03T16:27:54.540Z

Updated: 2024-11-14T21:02:40.473Z

Reserved: 2024-09-06T11:47:59.783Z

Link: CVE-2024-8508

cve-icon Vulnrichment

Updated: 2024-11-14T21:02:40.473Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2024-10-03T17:15:15.323

Modified: 2024-10-04T13:50:43.727

Link: CVE-2024-8508

cve-icon Redhat

Severity : Moderate

Publid Date: 2024-10-03T16:27:54Z

Links: CVE-2024-8508 - Bugzilla