# CVE-2026-25518: GO-2026-4399 - DoS in cert-manager-controller via Specially Crafted DNS Response in github.com/cert-manager/cert-manager

Source: https://junglewise.ai/threats/cve-2026-25518-cert-manager-controller-dos-via-specially-crafted-dns-response  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-02-19  
License: CC BY 4.0 with a link back

CVE-2026-25518 · Severity: low · CVSS 3.1 · Published 2026-02-19

DoS in cert-manager-controller via Specially Crafted DNS Response in github.com/cert-manager/cert-manager

Technologies: [github.com/cert-manager/cert-manager (Go)](https://junglewise.ai/threats/technologies/github-com-cert-manager-cert-manager). Vendors: [Go](https://junglewise.ai/threats/vendors/go).

## Quick answers

**Is CVE-2026-25518 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-25518 being exploited in the wild.

**How severe is CVE-2026-25518?** Low severity, with a CVSS score of 3.1, published 19 February 2026.

**Which products and versions are affected?** github.com/cert-manager/cert-manager (Go) SEMVER:introduced=1.18.0,fixed=1.18.5, SEMVER:introduced=1.18.0,fixed=1.18.5,introduced=1.19.0,fixed=1.19.3.

**Is there a fix for CVE-2026-25518?** Yes. github.com/cert-manager/cert-manager (Go): upgrade to 1.18.5, 1.19.3 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**Am I affected by CVE-2026-25518?** Check whether you run github.com/cert-manager/cert-manager (Go) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- github.com/cert-manager/cert-manager (Go): upgrade to 1.18.5, 1.19.3 or later

  ```sh
  go get github.com/cert-manager/cert-manager@v1.19.3
  ```


## Affected products

- github.com/cert-manager/cert-manager (Go) SEMVER:introduced=1.18.0,fixed=1.18.5, SEMVER:introduced=1.18.0,fixed=1.18.5,introduced=1.19.0,fixed=1.19.3

## Identifiers

- CVE-2026-25518
- GHSA-gx3x-vq4p-mhhv
- GO-2026-4399

## Related threats

- [cert-manager authorization bypass in Challenge resource creation](https://junglewise.ai/threats/cve-2026-62290-cert-manager-authorization-bypass-in-challenge-resource-creation)
- [GO-2024-3282 - Potential slowdown / DoS when parsing specially crafted PEM inputs in github.com/cert-manager/cert-manager](https://junglewise.ai/threats/cve-2024-12401-duplicate-advisory-cert-manager-ha-a-potential-slowdown-dos-when)