CVE-2026-25518 cert-manager-controller DoS via Specially Crafted DNS Response
An attacker can cause a denial of service in the cert-manager controller by intercepting DNS traffic and injecting crafted entries that trigger a panic.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-25518?
CVE-2026-25518 is a medium-severity denial of service vulnerability in cert-manager, published on 4 Feb 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
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.
Which versions are affected by CVE-2026-25518?
6 open source packages ship an affected version, including github.com/cert-manager/cert-manager and cert-manager. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
github.com/cert-manager/cert-manager Go | From 1.18.0 | 1.18.5, 1.19.3 |
github.com/cert-manager/cert-manager Go | From 1.18.0 | 1.18.5 |
github.com/cert-manager/cert-manager Go | From 1.18.0 | 1.18.5 |
github.com/cert-manager/cert-manager Go | From 1.19.0 | 1.19.3 |
github.com/cert-manager/cert-manager Go | From 1.19.0 | 1.19.3 |
cert-manager Bitnami | From 1.18.0 | 1.18.5, 1.19.3 |
Products include Cert-Manager Cert-Manager.
How do I fix CVE-2026-25518?
Upgrade github.com/cert-manager/cert-manager to a fixed version for your release line: 1.18.5 or 1.19.3.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-25518 being exploited?
There is no known exploitation of CVE-2026-25518 in the wild and no public exploit code.
Other vulnerabilities in cert-manager
Sources
Also known as BIT-cert-manager-2026-25518, CLEANSTART-2026-LX31883, CLEANSTART-2026-OJ21892, GHSA-gx3x-vq4p-mhhv, GO-2026-4399, MINI-334r-v2v4-mvqr and 7 more.