CVE-2026-25518: Github.com/cert manager/cert manager Denial of Service Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-gx3x-vq4p-mhhv",
  "modified" : "2026-02-27T21:41:50Z",
  "published" : "2026-02-02T22:11:06Z",
  "aliases" : [ "CVE-2026-25518" ],
  "summary" : "cert-manager-controller DoS via Specially Crafted DNS Response",
  "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's 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!",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/cert-manager/cert-manager"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "1.18.0"
      }, {
        "fixed" : "1.18.5"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/cert-manager/cert-manager"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "1.19.0"
      }, {
        "fixed" : "1.19.3"
      } ]
    } ]
  } ],
  "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"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-129", "CWE-704" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-02-02T22:11:06Z",
    "nvd_published_at" : "2026-02-04T22:15:58Z"
  }
}