cert-manager adds certificates and certificate issuers as resource types in Kubernetes clusters, and simplifies the process of obtaining, renewing and using those certificates. In versions from 1.18.0 to before 1.18.5 and from 1.19.0 to before 1.19.3, the cert-manager-controller performs DNS lookups during ACME DNS-01 processing (for zone discovery and propagation self-checks). By default, these lookups use standard unencrypted DNS. An attacker who can intercept and modify DNS traffic from the cert-manager-controller pod can insert a crafted entry into cert-manager's DNS cache. Accessing this entry will trigger a panic, resulting in denial‑of‑service (DoS) of the cert-manager controller. The issue can also be exploited if the authoritative DNS server for the domain being validated is controlled by a malicious actor. This issue has been patched in versions 1.18.5 and 1.19.3.

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-gx3x-vq4p-mhhv cert-manager-controller DoS via Specially Crafted DNS Response
Fixes

Solution

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Workaround

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History

Wed, 04 Feb 2026 21:30:00 +0000

Type Values Removed Values Added
Description cert-manager adds certificates and certificate issuers as resource types in Kubernetes clusters, and simplifies the process of obtaining, renewing and using those certificates. In versions from 1.18.0 to before 1.18.5 and from 1.19.0 to before 1.19.3, the cert-manager-controller performs DNS lookups during ACME DNS-01 processing (for zone discovery and propagation self-checks). By default, these lookups use standard unencrypted DNS. An attacker who can intercept and modify DNS traffic from the cert-manager-controller pod can insert a crafted entry into cert-manager's DNS cache. Accessing this entry will trigger a panic, resulting in denial‑of‑service (DoS) of the cert-manager controller. The issue can also be exploited if the authoritative DNS server for the domain being validated is controlled by a malicious actor. This issue has been patched in versions 1.18.5 and 1.19.3.
Title cert-manager-controller DoS via Specially Crafted DNS Response
Weaknesses CWE-129
CWE-704
References
Metrics cvssV3_1

{'score': 5.9, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-02-04T21:18:06.681Z

Reserved: 2026-02-02T18:21:42.487Z

Link: CVE-2026-25518

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-02-04T22:15:58.990

Modified: 2026-02-04T22:15:58.990

Link: CVE-2026-25518

cve-icon Redhat

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cve-icon OpenCVE Enrichment

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Weaknesses