CVE-2026-31662 (GCVE-0-2026-31662)
Vulnerability from cvelistv5 – Published: 2026-04-24 14:45 – Updated: 2026-04-24 14:45
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 ?
No CVSS data available.
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) |
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{
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"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
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"status": "unaffected",
"version": "5.10.253",
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},
{
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"status": "unaffected",
"version": "5.15.203",
"versionType": "semver"
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{
"lessThanOrEqual": "6.1.*",
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"version": "6.1.169",
"versionType": "semver"
},
{
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"version": "6.6.135",
"versionType": "semver"
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{
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"version": "6.12.82",
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{
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"version": "6.18.23",
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{
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"version": "6.19.13",
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"descriptions": [
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"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."
}
],
"providerMetadata": {
"dateUpdated": "2026-04-24T14:45:12.593Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
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"references": [
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"url": "https://git.kernel.org/stable/c/a7db57ccca21f5801609065473c89a38229ecb92"
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{
"url": "https://git.kernel.org/stable/c/36ec4fdd6250dcd5e73eb09ea92ed92e9cc28412"
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{
"url": "https://git.kernel.org/stable/c/575faea557f1a184a5f09661bd47ebd3ef3769f8"
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{
"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",
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"cveId": "CVE-2026-31662",
"datePublished": "2026-04-24T14:45:12.593Z",
"dateReserved": "2026-03-09T15:48:24.129Z",
"dateUpdated": "2026-04-24T14:45:12.593Z",
"state": "PUBLISHED"
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"date": "2026-04-25",
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}
}
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Sightings
| Author | Source | Type | Date |
|---|
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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