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CVE-2026-81928

Estado: AplazadaAlta (7.5)—

Net::DNS versions before 1.57 for Perl allow memory exhaustion via unbounded recursion in sig_data when re-encoding a message with a misplaced TSIG record.

sig_data signs a message by re-encoding it, and removes TSIG records only from the additional section. A TSIG decoded into the answer or authority section survives that step and is signed again, so encoding re-enters sig_data with no termination condition. Decoding does not reject such a message: a TSIG that is not the last record on the wire raises "misplaced or corrupt TSIG", but the error is caught, reported as a warning, and the record is left in the packet. RFC 8945 section 5.2 requires the message to be dropped.

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The recursion is reached only when the decoded TSIG carries an empty MAC, since a MAC recovered from the wire short-circuits the signing step. It is reached only from code that re-encodes a message it decoded, such as a forwarder or a proxy. A decoded message that is never re-encoded is unaffected. Message direction does not matter: a query reaches the same path as a response.

Each cycle re-encodes the whole message, so fewer than 100 bytes on the wire exhaust available memory and terminate the process.

CVSS

Probabilidad de explotación (EPSS)

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

🎯 Técnicas ATT&CK

Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.

Vulnerabilidad remota sin autenticación (AV:N/PR:N) en servicio DNS que causa agotamiento de memoria mediante recursión no acotada al re-codificar mensajes con TSIG malformado, resultando en denegación de servicio.

Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.

🛡️ Mitigaciones ATT&CK que cubren estas técnicas

Filter Network TrafficVulnerability ScanningPrivileged Account ManagementNetwork SegmentationLimit Access to Resource Over NetworkApplication Isolation and Sandboxing

Tecnologías afectadas (1)

⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.

NET DNS — NET DNSAI

CWE

Referencias

JSON original (NVD)

Mostrar
{
  "id": "CVE-2026-81928",
  "cveTags": [],
  "metrics": {
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-81928",
          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2026-09-02T19:23:53.602465Z"
        }
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 7.5,
          "attackVector": "NETWORK",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 3.6,
        "exploitabilityScore": 3.9
      }
    ]
  },
  "affected": [
    {
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
      "affectedData": [
        {
          "repo": "https://www.net-dns.org/svn/net-dns/",
          "modules": [
            "Net::DNS"
          ],
          "versions": [
            {
              "status": "affected",
              "version": "0",
              "lessThan": "1.57",
              "versionType": "custom"
            }
          ],
          "packageURL": "pkg:cpan/Net-DNS",
          "packageName": "Net-DNS",
          "programFiles": [
            "lib/Net/DNS/RR/TSIG.pm"
          ],
          "collectionURL": "https://cpan.org/modules",
          "defaultStatus": "unaffected",
          "programRoutines": [
            {
              "name": "Net::DNS::RR::TSIG::sig_data"
            }
          ]
        }
      ]
    }
  ],
  "published": "2026-09-02T00:18:26.147",
  "references": [
    {
      "url": "https://datatracker.ietf.org/doc/html/rfc8945#section-5.2",
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e"
    },
    {
      "url": "https://metacpan.org/release/NLNETLABS/Net-DNS-1.56/source/lib/Net/DNS/RR/TSIG.pm#L245-262",
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e"
    },
    {
      "url": "https://metacpan.org/release/NLNETLABS/Net-DNS-1.56/source/lib/Net/DNS/RR/TSIG.pm#L62-73",
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e"
    },
    {
      "url": "https://metacpan.org/release/NLNETLABS/Net-DNS-1.57/changes",
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e"
    },
    {
      "url": "https://rt.cpan.org/Ticket/Display.html?id=181125",
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e"
    },
    {
      "url": "http://www.openwall.com/lists/oss-security/2026/09/02/1",
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    }
  ],
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
      "description": [
        {
          "lang": "en",
          "value": "CWE-674"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "Net::DNS versions before 1.57 for Perl allow memory exhaustion via unbounded recursion in sig_data when re-encoding a message with a misplaced TSIG record.\n\nsig_data signs a message by re-encoding it, and removes TSIG records only from the additional section. A TSIG decoded into the answer or authority section survives that step and is signed again, so encoding re-enters sig_data with no termination condition. Decoding does not reject such a message: a TSIG that is not the last record on the wire raises \"misplaced or corrupt TSIG\", but the error is caught, reported as a warning, and the record is left in the packet. RFC 8945 section 5.2 requires the message to be dropped.\n\nThe recursion is reached only when the decoded TSIG carries an empty MAC, since a MAC recovered from the wire short-circuits the signing step. It is reached only from code that re-encodes a message it decoded, such as a forwarder or a proxy. A decoded message that is never re-encoded is unaffected. Message direction does not matter: a query reaches the same path as a response.\n\nEach cycle re-encodes the whole message, so fewer than 100 bytes on the wire exhaust available memory and terminate the process."
    }
  ],
  "lastModified": "2026-09-03T16:41:09.297",
  "sourceIdentifier": "9b29abf9-4ab0-4765-b253-1875cd9b441e"
}