GHSA-GX3X-VQ4P-MHHV

Vulnerability from github – Published: 2026-02-02 22:11 – Updated: 2026-02-27 21:41
VLAI
Summary
cert-manager-controller DoS via Specially Crafted DNS Response
Details

Impact

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.

Patches

The vulnerability was introduced in cert-manager v1.18.0 and has been patched in cert-manager v1.19.3 and v1.18.5, which are the supported minor releases at the time of publishing.

cert-manager versions prior to v1.18.0 are unaffected.

Workarounds

  • Using DNS-over-HTTPS reduces the risk of DNS traffic being intercepted and modified.
    • Note that DNS-over-HTTPS does not prevent the risk of an attacker-controlled authoritative DNS server.

Resources

  • Fix for cert-manager 1.18: https://github.com/cert-manager/cert-manager/pull/8467
  • Fix for cert-manager 1.19: https://github.com/cert-manager/cert-manager/pull/8468
  • Fix for master branch: https://github.com/cert-manager/cert-manager/pull/8469

Credits

Huge thanks to Oleh Konko (@1seal) for reporting the issue, providing a detailed PoC and an initial patch!

Severity
5.9 (Medium)
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Show details on source website
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{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/cert-manager/cert-manager"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "1.18.0"
            },
            {
              "fixed": "1.18.5"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/cert-manager/cert-manager"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "1.19.0"
            },
            {
              "fixed": "1.19.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-25518"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-129",
      "CWE-704"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-02-02T22:11:06Z",
    "nvd_published_at": "2026-02-04T22:15:58Z",
    "severity": "MODERATE"
  },
  "details": "### Impact\n\nThe 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.\n\nAn attacker who can intercept and modify DNS traffic from the cert-manager-controller pod can insert a crafted entry into cert-manager\u0027s DNS cache. Accessing this entry will trigger a panic, resulting in Denial of Service (DoS) of the cert-manager controller.\n\nThe issue can also be exploited if the authoritative DNS server for the domain being validated is controlled by a malicious actor.\n\n### Patches\n\nThe vulnerability was introduced in cert-manager v1.18.0 and has been patched in cert-manager v1.19.3 and v1.18.5, which are the supported minor releases at the time of publishing.\n\ncert-manager versions prior to v1.18.0 are unaffected.\n\n### Workarounds\n\n- Using DNS-over-HTTPS reduces the risk of DNS traffic being intercepted and modified.\n    - Note that DNS-over-HTTPS does *not* prevent the risk of an attacker-controlled authoritative DNS server.\n\n### Resources\n\n- Fix for cert-manager 1.18: https://github.com/cert-manager/cert-manager/pull/8467\n- Fix for cert-manager 1.19: https://github.com/cert-manager/cert-manager/pull/8468\n- Fix for master branch: https://github.com/cert-manager/cert-manager/pull/8469\n\n### Credits\n\nHuge thanks to Oleh Konko (@1seal) for reporting the issue, providing a detailed PoC and an initial patch!",
  "id": "GHSA-gx3x-vq4p-mhhv",
  "modified": "2026-02-27T21:41:50Z",
  "published": "2026-02-02T22:11:06Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/cert-manager/cert-manager/security/advisories/GHSA-gx3x-vq4p-mhhv"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-25518"
    },
    {
      "type": "WEB",
      "url": "https://github.com/cert-manager/cert-manager/pull/8467"
    },
    {
      "type": "WEB",
      "url": "https://github.com/cert-manager/cert-manager/pull/8468"
    },
    {
      "type": "WEB",
      "url": "https://github.com/cert-manager/cert-manager/pull/8469"
    },
    {
      "type": "WEB",
      "url": "https://github.com/cert-manager/cert-manager/commit/409fc24e539711a07aae45ed45abbe03dfdad2cc"
    },
    {
      "type": "WEB",
      "url": "https://github.com/cert-manager/cert-manager/commit/9a73a0b3853035827edd37ac463e4803ba10327d"
    },
    {
      "type": "WEB",
      "url": "https://github.com/cert-manager/cert-manager/commit/d4faed26ae12115cceb807cdc12507ebc28980e2"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/cert-manager/cert-manager"
    },
    {
      "type": "WEB",
      "url": "https://pkg.go.dev/vuln/GO-2026-4399"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "cert-manager-controller DoS via Specially Crafted DNS Response"
}


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