Описание
Querying for records within a specially crafted zone containing certain malformed DNSKEY records can lead to CPU exhaustion.
This issue affects BIND 9 versions 9.18.0 through 9.18.39, 9.20.0 through 9.20.13, 9.21.0 through 9.21.12, 9.18.11-S1 through 9.18.39-S1, and 9.20.9-S1 through 9.20.13-S1.
A vulnerability was found in BIND 9 resolvers, where processing malformed DNSKEY records from a specially crafted zone can lead to resource exhaustion, primarily causing excessive CPU utilization. This issue enables a remote, unauthenticated attacker to degrade resolver performance and potentially cause a denial of service (DoS) for legitimate DNS clients.
Отчет
This vulnerability is considered Important because it allows a remote, unauthenticated attacker to cause significant CPU exhaustion on vulnerable BIND resolvers by serving zones containing malformed DNSKEY records. The flaw triggers excessive computational effort during DNSKEY validation, leading to degraded performance and potential denial of service for legitimate clients. However, the issue affects availability only—it does not enable code execution, data exposure, or privilege escalation—so it is not classified as critical. Furthermore, authoritative servers are not impacted, limiting the scope of exposure to recursive resolvers. While the attack is easy to launch and can disrupt DNS operations, its effect ceases once the malicious traffic stops, making prompt patching and recursive access control effective mitigations.
Меры по смягчению последствий
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability. To reduce risk, restrict recursive queries to trusted or internal networks only, and apply rate limiting or firewall rules to prevent excessive or repetitive requests. Enabling DNSSEC validation helps reject forged records, while isolating recursive resolvers from authoritative servers limits the impact of potential cache poisoning. Active monitoring of CPU usage, query volume, and cache anomalies can provide early warning of abuse or attacks.
Затронутые пакеты
| Платформа | Пакет | Состояние | Рекомендация | Релиз |
|---|---|---|---|---|
| Red Hat Enterprise Linux 6 | bind | Not affected | ||
| Red Hat Enterprise Linux 7 | bind | Not affected | ||
| Red Hat Enterprise Linux 8 | bind | Not affected | ||
| Red Hat Enterprise Linux 8 | bind9.16 | Not affected | ||
| Red Hat Enterprise Linux 9 | bind | Not affected | ||
| Red Hat Enterprise Linux 9 | dhcp | Not affected | ||
| Red Hat Enterprise Linux 10 | bind | Fixed | RHSA-2025:19912 | 06.11.2025 |
| Red Hat Enterprise Linux 10 | bind | Fixed | RHSA-2025:21034 | 11.11.2025 |
| Red Hat Enterprise Linux 9 | bind9.18 | Fixed | RHSA-2025:19950 | 10.11.2025 |
| Red Hat Enterprise Linux 9 | bind9.18 | Fixed | RHSA-2025:21111 | 12.11.2025 |
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Дополнительная информация
Статус:
EPSS
7.5 High
CVSS3
Связанные уязвимости
Querying for records within a specially crafted zone containing certain malformed DNSKEY records can lead to CPU exhaustion. This issue affects BIND 9 versions 9.18.0 through 9.18.39, 9.20.0 through 9.20.13, 9.21.0 through 9.21.12, 9.18.11-S1 through 9.18.39-S1, and 9.20.9-S1 through 9.20.13-S1.
Querying for records within a specially crafted zone containing certain malformed DNSKEY records can lead to CPU exhaustion. This issue affects BIND 9 versions 9.18.0 through 9.18.39, 9.20.0 through 9.20.13, 9.21.0 through 9.21.12, 9.18.11-S1 through 9.18.39-S1, and 9.20.9-S1 through 9.20.13-S1.
Querying for records within a specially crafted zone containing certai ...
Querying for records within a specially crafted zone containing certain malformed DNSKEY records can lead to CPU exhaustion. This issue affects BIND 9 versions 9.18.0 through 9.18.39, 9.20.0 through 9.20.13, 9.21.0 through 9.21.12, 9.18.11-S1 through 9.18.39-S1, and 9.20.9-S1 through 9.20.13-S1.
EPSS
7.5 High
CVSS3