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CVE-2026-31662— tipc: fix bc_ackers underflow on duplicate GRP_ACK_MSG

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于tipc中bc_ackers下溢，可能导致广播阻塞。

CVSS 7.5 · High EPSS 0.39% · P31

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux 2f487712b89376fce267223bbb0db93d393d4b09< a7db57ccca21f5801609065473c89a38229ecb92 affected
2f487712b89376fce267223bbb0db93d393d4b09< 36ec4fdd6250dcd5e73eb09ea92ed92e9cc28412 affected
2f487712b89376fce267223bbb0db93d393d4b09< 575faea557f1a184a5f09661bd47ebd3ef3769f8 affected
2f487712b89376fce267223bbb0db93d393d4b09< 3bcf7aca63f0bcd679ae28e9b99823c608e59ce3 affected
2f487712b89376fce267223bbb0db93d393d4b09< a2ea1ef0167d7a84730638d05c20ccdc421b14b6 affected
2f487712b89376fce267223bbb0db93d393d4b09< 1b6f13f626665cac67ba5a012765427680518711 affected
2f487712b89376fce267223bbb0db93d393d4b09< e0bb732eaf77f9ac2f2638bdac9e39b81e0a9682 affected
2f487712b89376fce267223bbb0db93d393d4b09< 48a5fe38772b6f039522469ee6131a67838221a8 affected
… +10 more rows
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I. Basic Information for CVE-2026-31662

Vulnerability Information
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Vulnerability Title
tipc: fix bc_ackers underflow on duplicate GRP_ACK_MSG
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于tipc中bc_ackers下溢，可能导致广播阻塞。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 2f487712b89376fce267223bbb0db93d393d4b09 ~ a7db57ccca21f5801609065473c89a38229ecb92 -
Linux Linux 4.15 -

II. Public POCs for CVE-2026-31662

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III. Intelligence Information for CVE-2026-31662

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Same Patch Batch · Linux · 2026-04-24 · 138 CVEs total

CVE-2026-31637 9.8 CRITICAL rxrpc: reject undecryptable rxkad response tickets
CVE-2026-31536 9.8 CRITICAL smb: server: let send_done handle a completion without IB_SEND_SIGNALED
CVE-2026-31589 9.8 CRITICAL mm: call ->free_folio() directly in folio_unmap_invalidate()
CVE-2026-31669 9.8 CRITICAL mptcp: fix slab-use-after-free in __inet_lookup_established
CVE-2026-31668 9.8 CRITICAL seg6: separate dst_cache for input and output paths in seg6 lwtunnel
CVE-2026-31649 9.8 CRITICAL net: stmmac: fix integer underflow in chain mode
CVE-2026-31633 9.8 CRITICAL rxrpc: Fix integer overflow in rxgk_verify_response()
CVE-2026-31607 9.8 CRITICAL usbip: validate number_of_packets in usbip_pack_ret_submit()
CVE-2026-31608 9.8 CRITICAL smb: server: avoid double-free in smb_direct_free_sendmsg after smb_direct_flush_send_list
CVE-2026-31609 9.8 CRITICAL smb: client: avoid double-free in smbd_free_send_io() after smbd_send_batch_flush()
CVE-2026-31657 9.8 CRITICAL batman-adv: hold claim backbone gateways by reference
CVE-2026-31659 9.8 CRITICAL batman-adv: reject oversized global TT response buffers
CVE-2026-31636 9.1 CRITICAL rxrpc: fix RESPONSE authenticator parser OOB read
CVE-2026-31588 8.8 HIGH KVM: x86: Use scratch field in MMIO fragment to hold small write values
CVE-2026-31570 8.8 HIGH can: gw: fix OOB heap access in cgw_csum_crc8_rel()
CVE-2026-31622 8.8 HIGH NFC: digital: Bounds check NFC-A cascade depth in SDD response handler
CVE-2026-31558 8.8 HIGH LoongArch: KVM: Make kvm_get_vcpu_by_cpuid() more robust
CVE-2026-31553 8.8 HIGH KVM: arm64: Fix the descriptor address in __kvm_at_swap_desc()
CVE-2026-31629 8.8 HIGH nfc: llcp: add missing return after LLCP_CLOSED checks
CVE-2026-31611 8.6 HIGH ksmbd: require 3 sub-authorities before reading sub_auth[2]

Showing top 20 of 138 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-31662

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