CVE-2026-31662 (GCVE-0-2026-31662)

Vulnerability from cvelistv5 – Published: 2026-04-24 14:45 – Updated: 2026-04-27 14:04
VLAI?
Title
tipc: fix bc_ackers underflow on duplicate GRP_ACK_MSG
Summary
In the Linux kernel, the following vulnerability has been resolved: tipc: fix bc_ackers underflow on duplicate GRP_ACK_MSG The GRP_ACK_MSG handler in tipc_group_proto_rcv() currently decrements bc_ackers on every inbound group ACK, even when the same member has already acknowledged the current broadcast round. Because bc_ackers is a u16, a duplicate ACK received after the last legitimate ACK wraps the counter to 65535. Once wrapped, tipc_group_bc_cong() keeps reporting congestion and later group broadcasts on the affected socket stay blocked until the group is recreated. Fix this by ignoring duplicate or stale ACKs before touching bc_acked or bc_ackers. This makes repeated GRP_ACK_MSG handling idempotent and prevents the underflow path.
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
Linux Linux Affected: 2f487712b89376fce267223bbb0db93d393d4b09 , < a7db57ccca21f5801609065473c89a38229ecb92 (git)
Affected: 2f487712b89376fce267223bbb0db93d393d4b09 , < 36ec4fdd6250dcd5e73eb09ea92ed92e9cc28412 (git)
Affected: 2f487712b89376fce267223bbb0db93d393d4b09 , < 575faea557f1a184a5f09661bd47ebd3ef3769f8 (git)
Affected: 2f487712b89376fce267223bbb0db93d393d4b09 , < 3bcf7aca63f0bcd679ae28e9b99823c608e59ce3 (git)
Affected: 2f487712b89376fce267223bbb0db93d393d4b09 , < a2ea1ef0167d7a84730638d05c20ccdc421b14b6 (git)
Affected: 2f487712b89376fce267223bbb0db93d393d4b09 , < 1b6f13f626665cac67ba5a012765427680518711 (git)
Affected: 2f487712b89376fce267223bbb0db93d393d4b09 , < e0bb732eaf77f9ac2f2638bdac9e39b81e0a9682 (git)
Affected: 2f487712b89376fce267223bbb0db93d393d4b09 , < 48a5fe38772b6f039522469ee6131a67838221a8 (git)
Create a notification for this product.
    Linux Linux Affected: 4.15
Unaffected: 0 , < 4.15 (semver)
Unaffected: 5.10.253 , ≤ 5.10.* (semver)
Unaffected: 5.15.203 , ≤ 5.15.* (semver)
Unaffected: 6.1.169 , ≤ 6.1.* (semver)
Unaffected: 6.6.135 , ≤ 6.6.* (semver)
Unaffected: 6.12.82 , ≤ 6.12.* (semver)
Unaffected: 6.18.23 , ≤ 6.18.* (semver)
Unaffected: 6.19.13 , ≤ 6.19.* (semver)
Unaffected: 7.0 , ≤ * (original_commit_for_fix)
Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/tipc/group.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "a7db57ccca21f5801609065473c89a38229ecb92",
              "status": "affected",
              "version": "2f487712b89376fce267223bbb0db93d393d4b09",
              "versionType": "git"
            },
            {
              "lessThan": "36ec4fdd6250dcd5e73eb09ea92ed92e9cc28412",
              "status": "affected",
              "version": "2f487712b89376fce267223bbb0db93d393d4b09",
              "versionType": "git"
            },
            {
              "lessThan": "575faea557f1a184a5f09661bd47ebd3ef3769f8",
              "status": "affected",
              "version": "2f487712b89376fce267223bbb0db93d393d4b09",
              "versionType": "git"
            },
            {
              "lessThan": "3bcf7aca63f0bcd679ae28e9b99823c608e59ce3",
              "status": "affected",
              "version": "2f487712b89376fce267223bbb0db93d393d4b09",
              "versionType": "git"
            },
            {
              "lessThan": "a2ea1ef0167d7a84730638d05c20ccdc421b14b6",
              "status": "affected",
              "version": "2f487712b89376fce267223bbb0db93d393d4b09",
              "versionType": "git"
            },
            {
              "lessThan": "1b6f13f626665cac67ba5a012765427680518711",
              "status": "affected",
              "version": "2f487712b89376fce267223bbb0db93d393d4b09",
              "versionType": "git"
            },
            {
              "lessThan": "e0bb732eaf77f9ac2f2638bdac9e39b81e0a9682",
              "status": "affected",
              "version": "2f487712b89376fce267223bbb0db93d393d4b09",
              "versionType": "git"
            },
            {
              "lessThan": "48a5fe38772b6f039522469ee6131a67838221a8",
              "status": "affected",
              "version": "2f487712b89376fce267223bbb0db93d393d4b09",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/tipc/group.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.15"
            },
            {
              "lessThan": "4.15",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.253",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.203",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.169",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.135",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.82",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.23",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.19.*",
              "status": "unaffected",
              "version": "6.19.13",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.0",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.10.253",
                  "versionStartIncluding": "4.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.15.203",
                  "versionStartIncluding": "4.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.169",
                  "versionStartIncluding": "4.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.135",
                  "versionStartIncluding": "4.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.82",
                  "versionStartIncluding": "4.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.23",
                  "versionStartIncluding": "4.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.19.13",
                  "versionStartIncluding": "4.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0",
                  "versionStartIncluding": "4.15",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "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."
        }
      ],
      "metrics": [
        {
          "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"
          }
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-04-27T14:04:47.160Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/a7db57ccca21f5801609065473c89a38229ecb92"
        },
        {
          "url": "https://git.kernel.org/stable/c/36ec4fdd6250dcd5e73eb09ea92ed92e9cc28412"
        },
        {
          "url": "https://git.kernel.org/stable/c/575faea557f1a184a5f09661bd47ebd3ef3769f8"
        },
        {
          "url": "https://git.kernel.org/stable/c/3bcf7aca63f0bcd679ae28e9b99823c608e59ce3"
        },
        {
          "url": "https://git.kernel.org/stable/c/a2ea1ef0167d7a84730638d05c20ccdc421b14b6"
        },
        {
          "url": "https://git.kernel.org/stable/c/1b6f13f626665cac67ba5a012765427680518711"
        },
        {
          "url": "https://git.kernel.org/stable/c/e0bb732eaf77f9ac2f2638bdac9e39b81e0a9682"
        },
        {
          "url": "https://git.kernel.org/stable/c/48a5fe38772b6f039522469ee6131a67838221a8"
        }
      ],
      "title": "tipc: fix bc_ackers underflow on duplicate GRP_ACK_MSG",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-31662",
    "datePublished": "2026-04-24T14:45:12.593Z",
    "dateReserved": "2026-03-09T15:48:24.129Z",
    "dateUpdated": "2026-04-27T14:04:47.160Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-31662",
      "date": "2026-05-05",
      "epss": "0.00068",
      "percentile": "0.20655"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-31662\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-04-24T15:16:45.820\",\"lastModified\":\"2026-04-27T20:17:55.973\",\"vulnStatus\":\"Analyzed\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"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.\"}],\"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}]},\"weaknesses\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-191\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"4.15.1\",\"versionEndExcluding\":\"5.10.253\",\"matchCriteriaId\":\"B17827E3-86FD-498B-B936-E57F1C08BF4A\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"5.11\",\"versionEndExcluding\":\"5.15.203\",\"matchCriteriaId\":\"20DDB3E9-AABF-4107-ADB0-5362AA067045\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"5.16\",\"versionEndExcluding\":\"6.1.169\",\"matchCriteriaId\":\"DBEC0E5D-641C-4E98-A6D9-5799B10CE451\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.2\",\"versionEndExcluding\":\"6.6.135\",\"matchCriteriaId\":\"15C1A1B2-14EE-494C-AF3E-D5A7BA640B39\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.7\",\"versionEndExcluding\":\"6.12.82\",\"matchCriteriaId\":\"02904CAE-71D2-45B3-9EC3-F6A9D18B6307\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.13\",\"versionEndExcluding\":\"6.18.23\",\"matchCriteriaId\":\"E9E09FDD-9EE3-4A56-92E2-2B30AFD0072F\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.19\",\"versionEndExcluding\":\"6.19.13\",\"matchCriteriaId\":\"1490EF9B-9080-481C-8D22-1306AAE664E4\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:4.15:-:*:*:*:*:*:*\",\"matchCriteriaId\":\"3B4D39AF-668B-442B-8085-639A6D4FA5AC\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*\",\"matchCriteriaId\":\"F253B622-8837-4245-BCE5-A7BF8FC76A16\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*\",\"matchCriteriaId\":\"4AE85AD8-4641-4E7C-A2F4-305E2CD9EE64\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*\",\"matchCriteriaId\":\"F666C8D8-6538-46D4-B318-87610DE64C34\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*\",\"matchCriteriaId\":\"02259FDA-961B-47BC-AE7F-93D7EC6E90C2\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:*\",\"matchCriteriaId\":\"58A9FEFF-C040-420D-8F0A-BFDAAA1DF258\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.0:rc6:*:*:*:*:*:*\",\"matchCriteriaId\":\"1D2315C0-D46F-4F85-9754-F9E5E11374A6\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.0:rc7:*:*:*:*:*:*\",\"matchCriteriaId\":\"512EE3A8-A590-4501-9A94-5D4B268D6138\"}]}]}],\"references\":[{\"url\":\"https://git.kernel.org/stable/c/1b6f13f626665cac67ba5a012765427680518711\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/36ec4fdd6250dcd5e73eb09ea92ed92e9cc28412\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/3bcf7aca63f0bcd679ae28e9b99823c608e59ce3\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/48a5fe38772b6f039522469ee6131a67838221a8\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/575faea557f1a184a5f09661bd47ebd3ef3769f8\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/a2ea1ef0167d7a84730638d05c20ccdc421b14b6\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/a7db57ccca21f5801609065473c89a38229ecb92\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/e0bb732eaf77f9ac2f2638bdac9e39b81e0a9682\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]}]}}"
  }
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




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.