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Vulnerability · Published Feb 4, 2026 · Assigned by GitHub_M

CVE-2026-25518cert-manager-controller DoS via Specially Crafted DNS Response

Medium 5.9

In plain English

A medium-severity security flaw in cert-manager from cert-manager. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 31% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)5.9Medium
Exploit odds (30 days)0.4%top 68.7% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Gogithub.com/cert-manager/cert-manager1.18.5GHSA-gx3x-vq4p-mhhv
Gogithub.com/cert-manager/cert-manager1.19.3GHSA-gx3x-vq4p-mhhv
Gogithub.com/cert-manager/cert-manager1.18.5, 1.19.3GO-2026-4399

Affected products (as reported)

VendorProductVersions
cert-manager cert-manager >= 1.18.0, < 1.18.5>= 1.19.0, < 1.19.3

Weakness: CWE-129, CWE-704 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

References