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Moderate severityNVD Advisory· Published Feb 4, 2026· Updated Feb 5, 2026

cert-manager-controller DoS via Specially Crafted DNS Response

CVE-2026-25518

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.

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Affected packages

Versions sourced from the GitHub Security Advisory.

PackageAffected versionsPatched versions
github.com/cert-manager/cert-managerGo
>= 1.18.0, < 1.18.51.18.5
github.com/cert-manager/cert-managerGo
>= 1.19.0, < 1.19.31.19.3

Affected products

41

Patches

Vulnerability mechanics

References

10

News mentions

0

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