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Fencer Vulns
medium 5.9

CVE-2026-25518 json

cert-manager-controller DoS via Specially Crafted DNS Response

published 2026-02-02 9 mo ago modified 2026-09-10 1 mo ago also BIT-cert-manager-2026-25518 , EUVD-2026-5341 , GHSA-gx3x-vq4p-mhhv , GO-2026-4399

cvss
5.9
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 31%
public exploits
0
none known

Summary

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.

Patch / fix

  • go github.com/cert-manager/cert-manager 1.18.5, 1.19.3
  • bitnami cert-manager 1.18.5, 1.19.3
  • cert-manager cert-manager 1.18.5, 1.19.3
  • govulncheck-vulndb openSUSE Leap 15.6 0.0.20260226T182644-150000.1.149.1

suse advisories SUSE-SU-2026:0757-1

  • govulncheck-vulndb openSUSE Leap 16.0 0.0.20260723T184607-160000.1.1

opensuse advisories openSUSE-SU-2026:21483-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-25518 updated cvss 5.9

github.com/cert-manager/cert-manager: cert-manager: Denial of Service via crafted DNS entry

  • Red Hat cert-manager Operator for Red Hat OpenShift cert-manager/cert-manager-operator-rhel9, cert-manager/jetstack-cert-manager-rhel9, cert-manager/cert-manager-istio-csr-rhel9, cert-manager/cert-manager-operator-bundle, cert-manager/jetstack-cert-manager-acmesolver-rhel9 Red Hat Cryostat 4 cryostat/cryostat-rhel9-operator Red Hat External Secrets Operator for Red Hat OpenShift external-secrets-operator/external-secrets-rhel9, external-secrets-operator/bitwarden-sdk-server-rhel9, external-secrets-operator/external-secrets-operator-rhel9, external-secrets-operator/external-secrets-operator-bundle Red Hat Multicluster Engine for Kubernetes multicluster-engine/assisted-service-8-rhel8, multicluster-engine/assisted-service-9-rhel9 Red Hat OpenShift Pipelines openshift-pipelines-client, openshift-pipelines/pipelines-pipelines-as-code-controller-rhel9 Red Hat OpenShift Serverless openshift-serverless-1/kn-eventing-filter-rhel9, openshift-serverless-1/kn-eventing-mtping-rhel9, openshift-serverless-1/kn-serving-webhook-rhel9, openshift-serverless-1/kn-eventing-ingress-rhel9, openshift-serverless-1/kn-eventing-jobsink-rhel9, openshift-serverless-1/kn-eventing-webhook-rhel9, +7 more
    +9 more products
    Red Hat Power monitoring for Red Hat OpenShift openshift-power-monitoring/kepler-rhel9, openshift-power-monitoring/power-monitoring-rhel9-operator, openshift-power-monitoring/power-monitoring-operator-bundle Red Hat Build of Kueue kueue/kueue-rhel9, kueue/kueue-rhel9-operator, kueue/kueue-operator-bundle, kueue/kueue-must-gather-rhel9 Red Hat Connectivity Link 1 rhcl-1/rhcl-rhel9-operator, rhcl-1/rhcl-operator-bundle Red Hat OpenShift AI (RHOAI) rhoai/odh-model-registry-rhel9, rhoai/odh-kueue-controller-rhel9, rhoai/odh-model-controller-rhel9, rhoai/odh-kuberay-operator-controller-rhel9 Red Hat OpenShift Container Platform 4 openshift4/ose-olm-catalogd-rhel9, openshift4/ose-olm-operator-controller-rhel9, openshift4/ose-agent-installer-api-server-rhel9 Red Hat OpenShift distributed tracing 3 rhosdt/opentelemetry-rhel8-operator, rhosdt/opentelemetry-target-allocator-rhel8 Red Hat OpenShift GitOps openshift-gitops-1/gitops-rhel8-operator Red Hat OpenStack Platform 18.0 rhoso-operators/openstack-rhel9-operator, rhoso-operators/telemetry-rhel9-operator, rhoso-operators/openstack-operator-bundle, rhoso-operators/rabbitmq-cluster-rhel9-operator Red Hat Security Profiles Operator compliance/openshift-security-profiles-rhel8-operator, compliance/openshift-security-profiles-operator-bundle
    affected: workaround, no fix available “Fix deferred”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
9 mo ago

Exploit prediction

0.37% chance of exploitation in the next 30 days, higher than 31% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
GitHub 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
OSV 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
go github.com/cert-manager/cert-manager
>=1.18.0, <1.18.5
>=1.19.0, <1.19.3
1.18.5
1.19.3
bitnami cert-manager
>=1.18.0, <1.18.5
>=1.19.0, <1.19.3
1.18.5
1.19.3

Affected products

  • cert-manager cert-manager

Classification

Weakness
  • CWE-129 Improper Validation of Array Index
  • CWE-704 Incorrect Type Conversion or Cast

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.