CVE-2026-74434

Estado: RecibidaCrítica (9.8)—

In the Linux kernel, the following vulnerability has been resolved:

rxrpc: Don't move a peeked OOB message onto the pending queue

rxrpc_recvmsg_oob() takes a received oob message off recvmsg_oobq and, if a response is needed, moves it onto the pending_oobq tree. However, only the unlink from recvmsg_oobq is guarded by MSG_PEEK; the move onto pending_oobq always runs.

As a result, reading a challenge with MSG_PEEK leaves the skb on recvmsg_oobq while also adding it to pending_oobq. Since struct sk_buff's rbnode shares storage with its next and prev pointers, rb_insert_color() overwrites the list linkage, and the skb, which holds a single reference, becomes reachable from both queues at once.

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When the socket is closed both queues are drained in turn. While draining recvmsg_oobq, __skb_unlink() follows the next and prev pointers that rbnode has overwritten and writes to a bad address. Also, as the skb holds a single reference but is freed from each queue, both the skb and the connection reference it holds are released twice. This leads to memory corruption and to a use-after-free caused by the connection refcount underflow.

MSG_PEEK does not consume the message from the queue, so only unlink it from recvmsg_oobq and then move it onto pending_oobq or free it when the message is actually consumed.

CVSS

Versión: 3.1
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Puntuación base: 9.8

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.63%
Percentil entre todas las CVEs puntuadas: 48
Fecha de la puntuación: 5/10/2026

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.

ExplotaciónT1190 Exploit Public-Facing Applicationinitial access60 %

Inferido por reglas deterministas a partir del vector CVSS y la CWE. Solo orientativo.

🛡️ Mitigaciones ATT&CK que cubren estas técnicas

Vulnerability Scanning Privileged Account Management Network Segmentation Limit Access to Resource Over Network Filter Network Traffic Application 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.

Linux — Linux Kernel^AI

Referencias

JSON original (NVD)

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{
  "id": "CVE-2026-74434",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 9.8,
          "attackVector": "NETWORK",
          "baseSeverity": "CRITICAL",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 5.9,
        "exploitabilityScore": 3.9
      }
    ]
  },
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5800b1cf3fd8ccab752a101865be1e76dac33142",
              "lessThan": "9ada3931beb37068fcb725b34b0398457009f343",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "5800b1cf3fd8ccab752a101865be1e76dac33142",
              "lessThan": "5f470cc883416fea6d3bce18ef96bf91dd49ffc3",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "5800b1cf3fd8ccab752a101865be1e76dac33142",
              "lessThan": "5801cff7d5d7b4e9d877dfb627b23eb63167f02c",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "net/rxrpc/recvmsg.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.16"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "6.16",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "6.18.40",
              "versionType": "semver",
              "lessThanOrEqual": "6.18.*"
            },
            {
              "status": "unaffected",
              "version": "7.1.5",
              "versionType": "semver",
              "lessThanOrEqual": "7.1.*"
            },
            {
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "net/rxrpc/recvmsg.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-08-15T06:22:45.510",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/5801cff7d5d7b4e9d877dfb627b23eb63167f02c",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/5f470cc883416fea6d3bce18ef96bf91dd49ffc3",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/9ada3931beb37068fcb725b34b0398457009f343",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nrxrpc: Don't move a peeked OOB message onto the pending queue\n\nrxrpc_recvmsg_oob() takes a received oob message off recvmsg_oobq and,\nif a response is needed, moves it onto the pending_oobq tree. However,\nonly the unlink from recvmsg_oobq is guarded by MSG_PEEK; the move onto\npending_oobq always runs.\n\nAs a result, reading a challenge with MSG_PEEK leaves the skb on\nrecvmsg_oobq while also adding it to pending_oobq. Since struct\nsk_buff's rbnode shares storage with its next and prev pointers,\nrb_insert_color() overwrites the list linkage, and the skb, which holds\na single reference, becomes reachable from both queues at once.\n\nWhen the socket is closed both queues are drained in turn. While\ndraining recvmsg_oobq, __skb_unlink() follows the next and prev\npointers that rbnode has overwritten and writes to a bad address. Also,\nas the skb holds a single reference but is freed from each queue, both\nthe skb and the connection reference it holds are released twice. This\nleads to memory corruption and to a use-after-free caused by the\nconnection refcount underflow.\n\nMSG_PEEK does not consume the message from the queue, so only unlink it\nfrom recvmsg_oobq and then move it onto pending_oobq or free it when\nthe message is actually consumed."
    }
  ],
  "lastModified": "2026-08-17T06:19:39.030",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}