{"api_version":"1","generated_at":"2026-04-25T18:36:40+00:00","cve":"CVE-2026-31662","urls":{"html":"https://cve.report/CVE-2026-31662","api":"https://cve.report/api/cve/CVE-2026-31662.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-31662","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-31662"},"summary":{"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":"PUBLISHED","assigner":"Linux","published_at":"2026-04-24 15:16:45","updated_at":"2026-04-24 17:51:40"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/48a5fe38772b6f039522469ee6131a67838221a8","name":"https://git.kernel.org/stable/c/48a5fe38772b6f039522469ee6131a67838221a8","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/3bcf7aca63f0bcd679ae28e9b99823c608e59ce3","name":"https://git.kernel.org/stable/c/3bcf7aca63f0bcd679ae28e9b99823c608e59ce3","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/a2ea1ef0167d7a84730638d05c20ccdc421b14b6","name":"https://git.kernel.org/stable/c/a2ea1ef0167d7a84730638d05c20ccdc421b14b6","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/575faea557f1a184a5f09661bd47ebd3ef3769f8","name":"https://git.kernel.org/stable/c/575faea557f1a184a5f09661bd47ebd3ef3769f8","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/a7db57ccca21f5801609065473c89a38229ecb92","name":"https://git.kernel.org/stable/c/a7db57ccca21f5801609065473c89a38229ecb92","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/36ec4fdd6250dcd5e73eb09ea92ed92e9cc28412","name":"https://git.kernel.org/stable/c/36ec4fdd6250dcd5e73eb09ea92ed92e9cc28412","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/e0bb732eaf77f9ac2f2638bdac9e39b81e0a9682","name":"https://git.kernel.org/stable/c/e0bb732eaf77f9ac2f2638bdac9e39b81e0a9682","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/1b6f13f626665cac67ba5a012765427680518711","name":"https://git.kernel.org/stable/c/1b6f13f626665cac67ba5a012765427680518711","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-31662","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-31662","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 2f487712b89376fce267223bbb0db93d393d4b09 a7db57ccca21f5801609065473c89a38229ecb92 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 2f487712b89376fce267223bbb0db93d393d4b09 36ec4fdd6250dcd5e73eb09ea92ed92e9cc28412 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 2f487712b89376fce267223bbb0db93d393d4b09 575faea557f1a184a5f09661bd47ebd3ef3769f8 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 2f487712b89376fce267223bbb0db93d393d4b09 3bcf7aca63f0bcd679ae28e9b99823c608e59ce3 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 2f487712b89376fce267223bbb0db93d393d4b09 a2ea1ef0167d7a84730638d05c20ccdc421b14b6 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 2f487712b89376fce267223bbb0db93d393d4b09 1b6f13f626665cac67ba5a012765427680518711 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 2f487712b89376fce267223bbb0db93d393d4b09 e0bb732eaf77f9ac2f2638bdac9e39b81e0a9682 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 2f487712b89376fce267223bbb0db93d393d4b09 48a5fe38772b6f039522469ee6131a67838221a8 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4.15","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 4.15 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.10.253 5.10.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.15.203 5.15.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.1.169 6.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.135 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.82 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.23 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.19.13 6.19.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.0 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"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."}],"providerMetadata":{"dateUpdated":"2026-04-24T14:45:12.593Z","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":"2026-04-24T14:45:12.593Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-04-24 15:16:45","lastModifiedDate":"2026-04-24 17:51:40","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"31662","Ordinal":"1","Title":"tipc: fix bc_ackers underflow on duplicate GRP_ACK_MSG","CVE":"CVE-2026-31662","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"31662","Ordinal":"1","NoteData":"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.","Type":"Description","Title":"tipc: fix bc_ackers underflow on duplicate GRP_ACK_MSG"}]}}}