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CVE-2026-74282 (GCVE-0-2026-74282)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:57 – Updated: 2026-08-17 05:45
VLAI
Title
tipc: prevent snt_unacked underflow on CONN_ACK
Summary
In the Linux kernel, the following vulnerability has been resolved: tipc: prevent snt_unacked underflow on CONN_ACK tipc_sk_conn_proto_rcv() subtracts the peer-supplied connection ack count from the unsigned 16-bit send counter snt_unacked without checking that it does not exceed the number of messages actually outstanding: tsk->snt_unacked -= msg_conn_ack(hdr); msg_conn_ack() is read straight from a received CONN_MANAGER/CONN_ACK message. If the ack count is larger than snt_unacked, the subtraction wraps to a near-maximum value, leaving tsk_conn_cong() permanently true and starving the connection of further transmits. Validate the ACK count at the start of the CONN_ACK block and drop the message if it acknowledges more messages than are outstanding. A peer (or, for a local connection, the connected peer socket) can otherwise wedge a TIPC connection's send side by sending an oversized connection ack.
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: 10724cc7bb7832b482df049c20fd824d928c5eaa , < 3388145d258cf2c4c98278e3987296007d30672e (git)
Affected: 10724cc7bb7832b482df049c20fd824d928c5eaa , < 67e55b054bf8025658dc0e255057f2a6236416bd (git)
Affected: 10724cc7bb7832b482df049c20fd824d928c5eaa , < 96f91b8ae1a489b3eca137e7acf42cf985fb8939 (git)
Affected: 10724cc7bb7832b482df049c20fd824d928c5eaa , < 47ed873e4ceda34098bd46d8e96b4bb13cad3a04 (git)
Affected: 10724cc7bb7832b482df049c20fd824d928c5eaa , < b44bebdd32c9ff66ee2aebfc317ced44bedd9335 (git)
Affected: 10724cc7bb7832b482df049c20fd824d928c5eaa , < 3cfa3d8e0dc167850edeb5bf5a07757db83fd54e (git)
Affected: 10724cc7bb7832b482df049c20fd824d928c5eaa , < 1e2c956745777e6ffdee7f30da5935741c03ee1e (git)
Affected: 10724cc7bb7832b482df049c20fd824d928c5eaa , < ab3e10b44ba5411779aac7afd2477917dd77750f (git)
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Linux Linux Affected: 4.7
Unaffected: 0 , < 4.7 (semver)
Unaffected: 5.10.261 , ≤ 5.10.* (semver)
Unaffected: 5.15.212 , ≤ 5.15.* (semver)
Unaffected: 6.1.178 , ≤ 6.1.* (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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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntipc: prevent snt_unacked underflow on CONN_ACK\n\ntipc_sk_conn_proto_rcv() subtracts the peer-supplied connection ack count\nfrom the unsigned 16-bit send counter snt_unacked without checking that it\ndoes not exceed the number of messages actually outstanding:\n\n\ttsk-\u003esnt_unacked -= msg_conn_ack(hdr);\n\nmsg_conn_ack() is read straight from a received CONN_MANAGER/CONN_ACK\nmessage. If the ack count is larger than snt_unacked, the subtraction\nwraps to a near-maximum value, leaving tsk_conn_cong() permanently true\nand starving the connection of further transmits.\n\nValidate the ACK count at the start of the CONN_ACK block and drop the\nmessage if it acknowledges more messages than are outstanding. A peer (or,\nfor a local connection, the connected peer socket) can otherwise wedge a\nTIPC connection\u0027s send side by sending an oversized connection ack."
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            "version": "3.1"
          },
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              "lang": "en",
              "value": "AV:N - The flaw is reached when tipc_rcv() processes a remote CONN_MANAGER/CONN_ACK skb from a TIPC bearer (UDP port 6118 or Ethernet), traversing tipc_link_rcv()\u2192tipc_sk_rcv()\u2192tipc_sk_proto_rcv()\u2192tipc_sk_conn_proto_rcv() with attacker-controlled ack count.\nAC:L - After a normal TIPC connect handshake, the connected peer can send a single CONN_ACK whose msg_conn_ack() exceeds snt_unacked; no races, timing, or rare layout conditions are needed and the malicious field is fully attacker-controlled.\nPR:N - Exploitation only requires becoming the established TIPC peer via a standard AF_TIPC connect/listen handshake; socket creation needs no capabilities and the protocol has no authentication gate before CONN_ACK processing.\nUI:N - No victim user action is required beyond the service already accepting TIPC connections; the attacker triggers the bug by sending one crafted CONN_ACK on the established connection.\nS:U - Impact is limited to corrupting flow-control state on a victim TIPC socket within the same kernel/host security boundary; there is no VM escape, container breakout, or IOMMU boundary crossing.\nC:N - The unsigned 16-bit underflow only corrupts the snt_unacked congestion counter and does not read or disclose kernel memory, pointers, or other sensitive information.\nI:N - The bug modifies only an internal send-window counter to block transmits and provides no arbitrary write, code execution, or user/kernel data modification primitive.\nA:H - An oversized CONN_ACK wraps snt_unacked to a near-maximum value, leaving tsk_conn_cong() permanently true and indefinitely starving the victim socket\u0027s transmit path until the connection is torn down."
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        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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    "dateUpdated": "2026-08-17T05:45:23.387Z",
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If the ack count is larger than snt_unacked, the subtraction\\nwraps to a near-maximum value, leaving tsk_conn_cong() permanently true\\nand starving the connection of further transmits.\\n\\nValidate the ACK count at the start of the CONN_ACK block and drop the\\nmessage if it acknowledges more messages than are outstanding. A peer (or,\\nfor a local connection, the connected peer socket) can otherwise wedge a\\nTIPC connection\u0027s send side by sending an oversized connection ack.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"net/tipc/socket.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"10724cc7bb7832b482df049c20fd824d928c5eaa\",\"lessThan\":\"3388145d258cf2c4c98278e3987296007d30672e\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"10724cc7bb7832b482df049c20fd824d928c5eaa\",\"lessThan\":\"67e55b054bf8025658dc0e255057f2a6236416bd\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"10724cc7bb7832b482df049c20fd824d928c5eaa\",\"lessThan\":\"96f91b8ae1a489b3eca137e7acf42cf985fb8939\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"10724cc7bb7832b482df049c20fd824d928c5eaa\",\"lessThan\":\"47ed873e4ceda34098bd46d8e96b4bb13cad3a04\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"10724cc7bb7832b482df049c20fd824d928c5eaa\",\"lessThan\":\"b44bebdd32c9ff66ee2aebfc317ced44bedd9335\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"10724cc7bb7832b482df049c20fd824d928c5eaa\",\"lessThan\":\"3cfa3d8e0dc167850edeb5bf5a07757db83fd54e\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"10724cc7bb7832b482df049c20fd824d928c5eaa\",\"lessThan\":\"1e2c956745777e6ffdee7f30da5935741c03ee1e\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"10724cc7bb7832b482df049c20fd824d928c5eaa\",\"lessThan\":\"ab3e10b44ba5411779aac7afd2477917dd77750f\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"net/tipc/socket.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"4.7\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"4.7\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"5.10.261\",\"lessThanOrEqual\":\"5.10.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"5.15.212\",\"lessThanOrEqual\":\"5.15.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.1.178\",\"lessThanOrEqual\":\"6.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.6.145\",\"lessThanOrEqual\":\"6.6.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.97\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.40\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1.5\",\"lessThanOrEqual\":\"7.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H\",\"baseScore\":7.5,\"baseSeverity\":\"HIGH\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":3.9,\"impactScore\":3.6}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/1e2c956745777e6ffdee7f30da5935741c03ee1e\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/3388145d258cf2c4c98278e3987296007d30672e\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/3cfa3d8e0dc167850edeb5bf5a07757db83fd54e\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/47ed873e4ceda34098bd46d8e96b4bb13cad3a04\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/67e55b054bf8025658dc0e255057f2a6236416bd\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/96f91b8ae1a489b3eca137e7acf42cf985fb8939\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/ab3e10b44ba5411779aac7afd2477917dd77750f\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/b44bebdd32c9ff66ee2aebfc317ced44bedd9335\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-20T15:18:59+00:00",
      "cve": "CVE-2026-74282",
      "id": "CVE-2026-74282",
      "initial_release_date": "2026-08-15T00:00:00+00:00",
      "product_status:known_affected": "232",
      "product_status:known_not_affected": "42",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: tipc: prevent snt_unacked underflow on CONN_ACK",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-74282.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

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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.


Detection rules are retrieved from Rulezet.