{"id":"CVE-2026-31662","revision":null,"records":[{"revision":"69563ee170c4466dbd4ed288b39cfe13","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-31662","aliases":[],"title":"tipc: fix bc_ackers underflow on duplicate GRP_ACK_MSG","description":"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.","state":0,"publishedAt":"2026-04-24T14:45:12.593+00:00","modifiedAt":"2026-10-19T18:56:02.28+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"unaffected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"net/tipc/group.c\"\n ],\n \"versions\": [\n {\n \"version\": \"2f487712b89376fce267223bbb0db93d393d4b09\",\n \"lessThan\": \"a7db57ccca21f5801609065473c89a38229ecb92\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"2f487712b89376fce267223bbb0db93d393d4b09\",\n \"lessThan\": \"36ec4fdd6250dcd5e73eb09ea92ed92e9cc28412\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"2f487712b89376fce267223bbb0db93d393d4b09\",\n \"lessThan\": \"575faea557f1a184a5f09661bd47ebd3ef3769f8\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"2f487712b89376fce267223bbb0db93d393d4b09\",\n \"lessThan\": \"3bcf7aca63f0bcd679ae28e9b99823c608e59ce3\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"2f487712b89376fce267223bbb0db93d393d4b09\",\n \"lessThan\": \"a2ea1ef0167d7a84730638d05c20ccdc421b14b6\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"2f487712b89376fce267223bbb0db93d393d4b09\",\n \"lessThan\": \"1b6f13f626665cac67ba5a012765427680518711\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"2f487712b89376fce267223bbb0db93d393d4b09\",\n \"lessThan\": \"e0bb732eaf77f9ac2f2638bdac9e39b81e0a9682\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"2f487712b89376fce267223bbb0db93d393d4b09\",\n \"lessThan\": \"48a5fe38772b6f039522469ee6131a67838221a8\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n }\n ]\n }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"affected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"net/tipc/group.c\"\n ],\n \"versions\": [\n {\n \"version\": \"4.15\",\n \"status\": \"affected\"\n },\n {\n \"version\": \"0\",\n \"lessThan\": \"4.15\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"5.10.253\",\n \"lessThanOrEqual\": \"5.10.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"5.15.203\",\n \"lessThanOrEqual\": \"5.15.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.1.169\",\n \"lessThanOrEqual\": \"6.1.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.6.135\",\n \"lessThanOrEqual\": \"6.6.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.12.82\",\n \"lessThanOrEqual\": \"6.12.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.18.23\",\n \"lessThanOrEqual\": \"6.18.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.19.13\",\n \"lessThanOrEqual\": \"6.19.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.0\",\n \"lessThanOrEqual\": \"*\",\n \"status\": \"unaffected\",\n \"versionType\": \"original_commit_for_fix\"\n }\n ]\n }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5,"severity":"HIGH"}],"references":["https://git.kernel.org/stable/c/a7db57ccca21f5801609065473c89a38229ecb92","https://git.kernel.org/stable/c/36ec4fdd6250dcd5e73eb09ea92ed92e9cc28412","https://git.kernel.org/stable/c/575faea557f1a184a5f09661bd47ebd3ef3769f8","https://git.kernel.org/stable/c/3bcf7aca63f0bcd679ae28e9b99823c608e59ce3","https://git.kernel.org/stable/c/a2ea1ef0167d7a84730638d05c20ccdc421b14b6","https://git.kernel.org/stable/c/1b6f13f626665cac67ba5a012765427680518711","https://git.kernel.org/stable/c/e0bb732eaf77f9ac2f2638bdac9e39b81e0a9682","https://git.kernel.org/stable/c/48a5fe38772b6f039522469ee6131a67838221a8"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-31662","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-31662","identifiers":["CVE-2026-31662"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. 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