{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "2f487712b89376fce267223bbb0db93d393d4b09"
            },
            {
              "fixed": "a7db57ccca21f5801609065473c89a38229ecb92"
            },
            {
              "fixed": "36ec4fdd6250dcd5e73eb09ea92ed92e9cc28412"
            },
            {
              "fixed": "575faea557f1a184a5f09661bd47ebd3ef3769f8"
            },
            {
              "fixed": "3bcf7aca63f0bcd679ae28e9b99823c608e59ce3"
            },
            {
              "fixed": "a2ea1ef0167d7a84730638d05c20ccdc421b14b6"
            },
            {
              "fixed": "1b6f13f626665cac67ba5a012765427680518711"
            },
            {
              "fixed": "e0bb732eaf77f9ac2f2638bdac9e39b81e0a9682"
            },
            {
              "fixed": "48a5fe38772b6f039522469ee6131a67838221a8"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "4.15.0"
            },
            {
              "fixed": "5.10.253"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "5.11.0"
            },
            {
              "fixed": "5.15.203"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "5.16.0"
            },
            {
              "fixed": "6.1.169"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.2.0"
            },
            {
              "fixed": "6.6.135"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.7.0"
            },
            {
              "fixed": "6.12.82"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.13.0"
            },
            {
              "fixed": "6.18.23"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "6.19.13"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31662.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\ntipc: fix bc_ackers underflow on duplicate GRP_ACK_MSG\n\nThe GRP_ACK_MSG handler in tipc_group_proto_rcv() currently decrements\nbc_ackers on every inbound group ACK, even when the same member has\nalready acknowledged the current broadcast round.\n\nBecause bc_ackers is a u16, a duplicate ACK received after the last\nlegitimate ACK wraps the counter to 65535. Once wrapped,\ntipc_group_bc_cong() keeps reporting congestion and later group\nbroadcasts on the affected socket stay blocked until the group is\nrecreated.\n\nFix this by ignoring duplicate or stale ACKs before touching bc_acked or\nbc_ackers. This makes repeated GRP_ACK_MSG handling idempotent and\nprevents the underflow path.",
  "id": "CVE-2026-31662",
  "modified": "2026-07-08T05:36:17.513236937Z",
  "published": "2026-04-24T14:45:12.593Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1b6f13f626665cac67ba5a012765427680518711"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/36ec4fdd6250dcd5e73eb09ea92ed92e9cc28412"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3bcf7aca63f0bcd679ae28e9b99823c608e59ce3"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/48a5fe38772b6f039522469ee6131a67838221a8"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/575faea557f1a184a5f09661bd47ebd3ef3769f8"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a2ea1ef0167d7a84730638d05c20ccdc421b14b6"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a7db57ccca21f5801609065473c89a38229ecb92"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e0bb732eaf77f9ac2f2638bdac9e39b81e0a9682"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31662.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-31662"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.7.5",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "tipc: fix bc_ackers underflow on duplicate GRP_ACK_MSG"
}