Описание
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.
A flaw was found in Unbound which can lead to degraded performance and an eventual denial of service when handling replies with very large RRsets that require name compression to be applied. Versions prior to 1.21.1 do not have a hard limit on the number of name compression calculations that Unbound can perform per packet, meaning that if a specially crafted query is passed for the contents of a malicious zone with very large RRsets, Unbound may spend a considerable amount of time applying name compression to downstream replies, locking the CPU until the whole packet has been processed.
Отчет
Within regulated environments, a combination of the following controls acts as a significant barrier to successfully exploiting a CWE-606: Unchecked Input for Loop Condition vulnerability and therefore downgrades the severity of this particular CVE from Moderate to Low. Input validation controls are in place, which ensure that any input controlling loop behavior is validated against strict criteria like type, length, and range before being processed. This prevents malicious or abnormal inputs from causing excessive or infinite iterations, thereby avoiding logic errors or system overloads. Memory protection controls such as Data Execution Prevention (DEP) and Address Space Layout Randomization (ASLR) protect the system’s memory from overuse or corruption if an unchecked input were to cause a loop to execute excessively. It ensures that memory is safely allocated and accessed, reducing the risks of buffer overflows, resource exhaustion, or crashes. Lastly, the implementation of security engineering principles dictates the use of secure coding practices such as input validation, loop iteration limits, and error handling, which are integrated during system design and development.
Затронутые пакеты
| Платформа | Пакет | Состояние | Рекомендация | Релиз |
|---|---|---|---|---|
| Red Hat Enterprise Linux 7 | unbound | Out of support scope | ||
| Red Hat OpenStack Platform 16.2 | openstack-unbound-container | Out of support scope | ||
| Red Hat OpenStack Platform 17.1 | openstack-unbound-container | Affected | ||
| Red Hat OpenStack Platform 18.0 | openstack-unbound-container | Not affected | ||
| Red Hat Enterprise Linux 10 | unbound | Fixed | RHSA-2025:8047 | 20.05.2025 |
| Red Hat Enterprise Linux 8 | unbound | Fixed | RHSA-2025:0837 | 30.01.2025 |
| Red Hat Enterprise Linux 9 | unbound | Fixed | RHSA-2024:11232 | 17.12.2024 |
| Red Hat Enterprise Linux 9 | unbound | Fixed | RHSA-2025:8197 | 27.05.2025 |
| Red Hat Enterprise Linux 9.4 Extended Update Support | unbound | Fixed | RHSA-2024:11170 | 17.12.2024 |
| Red Hat OpenShift Container Platform 4.16 | rhcos-416.94.202501030250 | Fixed | RHSA-2025:0140 | 15.01.2025 |
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Дополнительная информация
Статус:
EPSS
5.3 Medium
CVSS3
Связанные уязвимости
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 ...
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 avo
NLnet Labs Unbound up to and including version 1.21.0 contains a vulne ...
EPSS
5.3 Medium
CVSS3