Skip to content
Heist/ feed
High

tipc: fix bc_ackers underflow on duplicate GRP_ACK_MSG

Type: advisorySource: Official CVE List1 source record

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.

Announced Source revision 1
Original source ↗

CVE-2026-31662

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-31662

Linux

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Linux

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "2f487712b89376fce267223bbb0db93d393d4b09",
        "lessThan": "a7db57ccca21f5801609065473c89a38229ecb92",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "2f487712b89376fce267223bbb0db93d393d4b09",
        "lessThan": "36ec4fdd6250dcd5e73eb09ea92ed92e9cc28412",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "2f487712b89376fce267223bbb0db93d393d4b09",
        "lessThan": "575faea557f1a184a5f09661bd47ebd3ef3769f8",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "2f487712b89376fce267223bbb0db93d393d4b09",
        "lessThan": "3bcf7aca63f0bcd679ae28e9b99823c608e59ce3",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "2f487712b89376fce267223bbb0db93d393d4b09",
        "lessThan": "a2ea1ef0167d7a84730638d05c20ccdc421b14b6",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "2f487712b89376fce267223bbb0db93d393d4b09",
        "lessThan": "1b6f13f626665cac67ba5a012765427680518711",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "2f487712b89376fce267223bbb0db93d393d4b09",
        "lessThan": "e0bb732eaf77f9ac2f2638bdac9e39b81e0a9682",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "2f487712b89376fce267223bbb0db93d393d4b09",
        "lessThan": "48a5fe38772b6f039522469ee6131a67838221a8",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "net/tipc/group.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "4.15"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "4.15",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "5.10.253",
        "versionType": "semver",
        "lessThanOrEqual": "5.10.*"
      },
      {
        "status": "unaffected",
        "version": "5.15.203",
        "versionType": "semver",
        "lessThanOrEqual": "5.15.*"
      },
      {
        "status": "unaffected",
        "version": "6.1.169",
        "versionType": "semver",
        "lessThanOrEqual": "6.1.*"
      },
      {
        "status": "unaffected",
        "version": "6.6.135",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.82",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.23",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "6.19.13",
        "versionType": "semver",
        "lessThanOrEqual": "6.19.*"
      },
      {
        "status": "unaffected",
        "version": "7.0",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "net/tipc/group.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-31662

Source reference: /cveMetadata/cveId

Publisher severity

high

Source reference: /containers/cna/metrics

Event
#39942 · Revision 1
Added to Heist Feed
Publisher date
Read the original announcement