CVE-2026-80588 (GCVE-0-2026-80588)

Vulnerability from cvelistv5 – Published: 2026-08-26 14:37 – Updated: 2026-08-27 05:02
VLAI
Title
mptcp: reclaim forward-allocated memory on RX path errors
Summary
In the Linux kernel, the following vulnerability has been resolved: mptcp: reclaim forward-allocated memory on RX path errors After commit 9db5b3cec4ec ("mptcp: borrow forward memory from subflow"), errors in the receive path prior to queueing skbs into the receive queue do not trigger forward-allocated memory reclaiming. Prevent forward memory from growing unboundedly in pathological drop scenarios by explicitly reclaiming memory when skbs are dropped.
Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: a84164847b1e0a106ebc46821e5d2f9b775c9dc8 , < 473f1a5ab2abc98dd9e74b95b9c23c66c47535cc (git)
Affected: 9db5b3cec4ec1c0cd3239689f5c8653d691a1754 , < 8277f48a06d3aa1441f6d0b6998ccc0360d30ed8 (git)
Affected: 9db5b3cec4ec1c0cd3239689f5c8653d691a1754 , < 41b49a8b914ec7dcb03eae93fb27f3c464078644 (git)
Affected: 6.18.35 , < 6.18.46 (semver)
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Linux Linux Affected: 6.19
Unaffected: 0 , < 6.19 (semver)
Unaffected: 6.18.46 , ≤ 6.18.* (semver)
Unaffected: 7.1.10 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/mptcp/protocol.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
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              "versionType": "git"
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          "vendor": "Linux",
          "versions": [
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              "version": "6.19"
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              "versionType": "semver"
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      "cpeApplicability": [
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                  "versionStartIncluding": "6.18.35",
                  "vulnerable": true
                },
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                  "versionStartIncluding": "6.19",
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                  "vulnerable": true
                }
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              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmptcp: reclaim forward-allocated memory on RX path errors\n\nAfter commit 9db5b3cec4ec (\"mptcp: borrow forward memory from subflow\"),\nerrors in the receive path prior to queueing skbs into the receive\nqueue do not trigger forward-allocated memory reclaiming.\n\nPrevent forward memory from growing unboundedly in pathological drop\nscenarios by explicitly reclaiming memory when skbs are dropped."
        }
      ],
      "metrics": [
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          "cvssV3_1": {
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - Remote TCP/MPTCP peers reach the bug on the established-connection RX datapath (tcp_rcv_established \u2192 subflow_data_ready \u2192 mptcp_data_ready \u2192 __mptcp_move_skbs_from_subflow \u2192 __mptcp_move_skb \u2192 mptcp_drop) when duplicate or out-of-window mapped data is dropped before skb_set_owner_r().\nAC:L - The attacker fully controls subflow packet contents and ordering on their MPTCP connection and can deterministically trigger drops (duplicate map_seq, OoO beyond rcv_wnd) on every crafted segment without races, rare sysctl state, or uncontrollable memory layout.\nPR:N - No local account or kernel capability is required on the victim; any remote peer that completes the TCP/MPTCP handshake on an IPPROTO_MPTCP socket (Android clients, MPTCP-enabled servers, curl --mptcp) can flood pathological RX drops without target credentials.\nUI:N - Exploitation needs only attacker-generated MPTCP/TCP traffic on an existing or attacker-initiated connection; no victim mount, file open, click, or other cooperative user action beyond normal network stack processing.\nS:U - Impact is unbounded sk_forward_alloc growth and kernel memory exhaustion on the affected host; it does not cross VM, container, IOMMU, or sandbox boundaries to another security authority.\nC:N - This is a forward-memory accounting leak on skb drop after mptcp_borrow_fwdmem(); skb data is freed and no use-after-free, out-of-bounds read, or other memory-corruption primitive exposes kernel contents to the attacker.\nI:N - The flaw only fails to reclaim borrowed forward allocation when dropping skbs; it does not corrupt, overwrite, or modify attacker-chosen memory and provides no write or code-execution primitive.\nA:H - Each pre-queue drop leaks roughly skb-\u003etruesize forward memory while bypassing the removed sk_rmem_schedule guard, so a remote peer can repeatedly trigger unbounded per-connection kernel memory growth and OOM denial of service, matching CNA precedent for repeatable network skb/memory leaks."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-27T05:02:09.335Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/473f1a5ab2abc98dd9e74b95b9c23c66c47535cc"
        },
        {
          "url": "https://git.kernel.org/stable/c/8277f48a06d3aa1441f6d0b6998ccc0360d30ed8"
        },
        {
          "url": "https://git.kernel.org/stable/c/41b49a8b914ec7dcb03eae93fb27f3c464078644"
        }
      ],
      "title": "mptcp: reclaim forward-allocated memory on RX path errors",
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        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-80588",
    "datePublished": "2026-08-26T14:37:42.685Z",
    "dateReserved": "2026-08-26T14:34:25.770Z",
    "dateUpdated": "2026-08-27T05:02:09.335Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
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      "date": "2026-09-01",
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      "percentile": "0.26605"
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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-27T15:58:50+00:00",
      "cve": "CVE-2026-80588",
      "id": "CVE-2026-80588",
      "initial_release_date": "2026-08-26T00:00:00+00:00",
      "product_status:known_affected": "184",
      "product_status:known_not_affected": "90",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: mptcp: reclaim forward-allocated memory on RX path errors",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-80588.json",
      "version": "3"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.