CVE-2026-72330 (GCVE-0-2026-72330)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:55 – Updated: 2026-08-17 05:42
VLAI
Title
net/tls: Consume empty data records in tls_sw_read_sock()
Summary
In the Linux kernel, the following vulnerability has been resolved: net/tls: Consume empty data records in tls_sw_read_sock() A peer may send a zero-length TLS application_data record; TLS 1.3 explicitly permits these as a traffic-analysis countermeasure (RFC 8446, Section 5.1). After decryption such a record has full_len == 0. tls_sw_read_sock() hands it to the read_actor, which has no payload to consume and returns zero. The loop treats a zero return as backpressure (used <= 0), requeues the skb at the head of rx_list, and stops. rx_list is serviced head-first on the next call, so the empty record is dequeued, fails the same way, and is requeued again; every later record on the connection is blocked behind it. tls_sw_recvmsg() does not stall on this: a zero-length data record copies nothing and falls through to consume_skb(). Mirror that in the read_sock() path by recognizing an empty data record before the actor runs, consuming it, and continuing.
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: 662fbcec32f4af6bdcf5b4006b792ebe9543d945 , < 0867b0f2513ebc1c475af9898c97f4772a68d964 (git)
Affected: 662fbcec32f4af6bdcf5b4006b792ebe9543d945 , < c6b440cf766a557b08d25f1b571b3d57d039686e (git)
Affected: 662fbcec32f4af6bdcf5b4006b792ebe9543d945 , < e8a4c9fc437b16aef38f86ce3275677e36924259 (git)
Affected: 662fbcec32f4af6bdcf5b4006b792ebe9543d945 , < ebc295ce343600c2d60c1e1e0c5d192080217457 (git)
Affected: 662fbcec32f4af6bdcf5b4006b792ebe9543d945 , < 3be28e2c9cd0230cb51fd4967df095273afd3848 (git)
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Linux Linux Affected: 6.6
Unaffected: 0 , < 6.6 (semver)
Unaffected: 6.6.145 , ≤ 6.6.* (semver)
Unaffected: 6.12.97 , ≤ 6.12.* (semver)
Unaffected: 6.18.40 , ≤ 6.18.* (semver)
Unaffected: 7.1.5 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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              "operator": "OR"
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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/tls: Consume empty data records in tls_sw_read_sock()\n\nA peer may send a zero-length TLS application_data record; TLS 1.3\nexplicitly permits these as a traffic-analysis countermeasure (RFC\n8446, Section 5.1). After decryption such a record has full_len ==\n0. tls_sw_read_sock() hands it to the read_actor, which has no\npayload to consume and returns zero. The loop treats a zero return\nas backpressure (used \u003c= 0), requeues the skb at the head of\nrx_list, and stops. rx_list is serviced head-first on the next\ncall, so the empty record is dequeued, fails the same way, and is\nrequeued again; every later record on the connection is blocked\nbehind it.\n\ntls_sw_recvmsg() does not stall on this: a zero-length data record\ncopies nothing and falls through to consume_skb(). Mirror that in\nthe read_sock() path by recognizing an empty data record before\nthe actor runs, consuming it, and continuing."
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              "value": "AV:N - A remote TLS peer sends zero-length TLS 1.3 application_data records over TCP; they are decrypted in the kTLS software RX path and processed in tls_sw_read_sock(), reachable from network-facing consumers such as NVMe-over-TCP host I/O via sock-\u003eops-\u003eread_sock.\nAC:L - After a normal TLS handshake, sending a standards-compliant zero-length application_data record reliably reproduces the stall; no races, special memory layout, or rare timing are required.\nPR:N - Exploitation requires only being the remote TLS peer on an established kTLS connection (e.g. a malicious NVMe-oF target); no local account, capability, namespace, or administrator privileges on the victim host are needed.\nUI:N - No victim user action beyond the system maintaining its normal encrypted network connection; the attacker triggers the flaw by sending protocol-valid TLS records.\nS:U - Impact is confined to stalling the affected TLS/kTLS connection and its dependent service I/O; it does not cross a security boundary such as guest-to-host escape or sandbox breakout.\nC:N - The flaw is a receive-path logic error that requeues an empty skb indefinitely; there is no out-of-bounds access, use-after-free, or other memory corruption that could disclose kernel or application data.\nI:N - The bug does not modify kernel memory, credentials, or application data; it only prevents forward progress on the stalled connection by blocking consumption of subsequent decrypted records.\nA:H - The empty record is permanently requeued at the head of rx_list, creating a repeatable deadlock that blocks all later traffic on the connection and can hang NVMe-over-TCP (or similar read_sock) I/O until the connection is torn down."
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    "datePublished": "2026-08-15T05:55:40.555Z",
    "dateReserved": "2026-08-09T03:40:39.919Z",
    "dateUpdated": "2026-08-17T05:42:52.302Z",
    "state": "PUBLISHED"
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            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/tls: Consume empty data records in tls_sw_read_sock()\n\nA peer may send a zero-length TLS application_data record; TLS 1.3\nexplicitly permits these as a traffic-analysis countermeasure (RFC\n8446, Section 5.1). After decryption such a record has full_len ==\n0. tls_sw_read_sock() hands it to the read_actor, which has no\npayload to consume and returns zero. The loop treats a zero return\nas backpressure (used \u003c= 0), requeues the skb at the head of\nrx_list, and stops. rx_list is serviced head-first on the next\ncall, so the empty record is dequeued, fails the same way, and is\nrequeued again; every later record on the connection is blocked\nbehind it.\n\ntls_sw_recvmsg() does not stall on this: a zero-length data record\ncopies nothing and falls through to consume_skb(). Mirror that in\nthe read_sock() path by recognizing an empty data record before\nthe actor runs, consuming it, and continuing."
          }
        ],
        "id": "CVE-2026-72330",
        "lastModified": "2026-08-17T06:18:36.580",
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                "baseScore": 7.5,
                "baseSeverity": "HIGH",
                "confidentialityImpact": "NONE",
                "integrityImpact": "NONE",
                "privilegesRequired": "NONE",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
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      "current_release_date": "2026-08-18T23:49:33+00:00",
      "cve": "CVE-2026-72330",
      "id": "CVE-2026-72330",
      "initial_release_date": "2026-08-15T00:00:00+00:00",
      "product_status:known_affected": "184",
      "product_status:known_not_affected": "90",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: net/tls: Consume empty data records in tls_sw_read_sock()",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-72330.json",
      "version": "3"
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      "current_release_date": "2026-09-05T00:29:18Z",
      "cve": "CVE-2026-72330",
      "id": "CVE-2026-72330",
      "initial_release_date": "2026-09-01T13:30:06Z",
      "product_status:known_not_affected": "362",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-72330",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-72330.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.

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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.


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