{"id":"CVE-2026-64450","state":"PUBLISHED","title":"tipc: fix out-of-bounds read in broadcast Gap ACK blocks","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ntipc: fix out-of-bounds read in broadcast Gap ACK blocks\n\nA broadcast PROTOCOL/STATE_MSG can carry a Gap ACK blocks record in its\ndata area. tipc_get_gap_ack_blks() only verifies that the record's len\nfield is self-consistent with its ugack_cnt/bgack_cnt counts\n(sz == struct_size(p, gacks, ugack_cnt + bgack_cnt)); it does not check\nthat the record actually fits in the message data area, msg_data_sz().\n\nThe unicast caller tipc_link_proto_rcv() bounds it (\"if (glen > dlen)\nbreak;\"), but the broadcast caller tipc_bcast_sync_rcv() discards the\nreturned size, so tipc_link_advance_transmq() copies the record off the\nreceive skb with an attacker-controlled count:\n\n\tthis_ga = kmemdup(ga, struct_size(ga, gacks, ga->bgack_cnt),\n\t\t\t  GFP_ATOMIC);\n\nA TIPC neighbour that negotiated TIPC_GAP_ACK_BLOCK triggers it with one\nordinary broadcast STATE_MSG (msg_bc_ack_invalid() clear), sized so its\ndata area is short, carrying a Gap ACK record with len = 0x400,\nbgack_cnt = 0xff and ugack_cnt = 0. len then equals\nstruct_size(p, gacks, 255), so the consistency check passes and ga is\nnon-NULL; kmemdup() reads struct_size(ga, gacks, 255) = 1024 bytes out\nof the much smaller skb:\n\n  BUG: KASAN: slab-out-of-bounds in kmemdup_noprof+0x48/0x60\n  Read of size 1024 at addr ffff0000c7030d38 by task poc864/69\n  Call trace:\n   kmemdup_noprof+0x48/0x60\n   tipc_link_advance_transmq+0x86c/0xb80\n   tipc_link_bc_ack_rcv+0x19c/0x1e0\n   tipc_bcast_sync_rcv+0x1c4/0x2c4\n   tipc_rcv+0x85c/0x1340\n   tipc_l2_rcv_msg+0xac/0x104\n  The buggy address belongs to the object at ffff0000c7030d00\n   which belongs to the cache skbuff_small_head of size 704\n  The buggy address is located 56 bytes inside of\n   allocated 704-byte region [ffff0000c7030d00, ffff0000c7030fc0)\n\nThe copied-out bytes are subsequently consumed as gap/ack values, but\nthe read is already out of bounds at the kmemdup() regardless of how\nthey are used.\n\nThe unicast STATE path drops such a message: \"if (glen > dlen) break;\"\nskips the rest of STATE_MSG handling and the skb is freed. Make the\nbroadcast path drop it too. tipc_bcast_sync_rcv() now bounds the record\nagainst msg_data_sz() and, when it does not fit, reports it back through\ntipc_node_bc_sync_rcv() to tipc_rcv() so the skb is discarded rather than\nprocessed. ga is not cleared on this path: ga == NULL already means\n\"legacy peer without Selective ACK\", a distinct legitimate state.","publishedAt":"2026-07-25T08:51:20.319Z","updatedAt":"2026-10-19T20:38:30.286Z","severity":{"score":9.1,"label":"Critical","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"d7626b5acff9227e2a65da636a53e09bdafdc0aa","status":"affected","lessThan":"055663d21dc4336f67933ab26bef3c5934be6324","versionType":"git"},{"version":"d7626b5acff9227e2a65da636a53e09bdafdc0aa","status":"affected","lessThan":"016f5995c37a5a2c45198308f830f244517d70b7","versionType":"git"},{"version":"d7626b5acff9227e2a65da636a53e09bdafdc0aa","status":"affected","lessThan":"74b45af86a767594ba52330cd440ea84e24d700d","versionType":"git"},{"version":"d7626b5acff9227e2a65da636a53e09bdafdc0aa","status":"affected","lessThan":"9a51115fcdc78687c8852bf93a1db3951dbb223b","versionType":"git"},{"version":"d7626b5acff9227e2a65da636a53e09bdafdc0aa","status":"affected","lessThan":"a21ed5064217cc33726da6c7ef1a520eba43aea1","versionType":"git"},{"version":"d7626b5acff9227e2a65da636a53e09bdafdc0aa","status":"affected","lessThan":"2de42e268174766cb2e2b90721afdfdff70e0d8d","versionType":"git"},{"version":"d7626b5acff9227e2a65da636a53e09bdafdc0aa","status":"affected","lessThan":"f333b6851bdf326fd2134133272dbbed0c94d921","versionType":"git"},{"version":"d7626b5acff9227e2a65da636a53e09bdafdc0aa","status":"affected","lessThan":"2b66974a1b6134a4bbc3bfed181f7418f688eb54","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/tipc/bcast.c","net/tipc/bcast.h","net/tipc/node.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.8","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.8","versionType":"semver"},{"version":"5.10.261","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.212","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.178","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.145","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.96","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.39","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.4","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/tipc/bcast.c","net/tipc/bcast.h","net/tipc/node.c"]}],"references":["https://git.kernel.org/stable/c/055663d21dc4336f67933ab26bef3c5934be6324","https://git.kernel.org/stable/c/016f5995c37a5a2c45198308f830f244517d70b7","https://git.kernel.org/stable/c/74b45af86a767594ba52330cd440ea84e24d700d","https://git.kernel.org/stable/c/9a51115fcdc78687c8852bf93a1db3951dbb223b","https://git.kernel.org/stable/c/a21ed5064217cc33726da6c7ef1a520eba43aea1","https://git.kernel.org/stable/c/2de42e268174766cb2e2b90721afdfdff70e0d8d","https://git.kernel.org/stable/c/f333b6851bdf326fd2134133272dbbed0c94d921","https://git.kernel.org/stable/c/2b66974a1b6134a4bbc3bfed181f7418f688eb54"],"weaknesses":["CWE-125"],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/64xxx/CVE-2026-64450.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-64450","state":"PUBLISHED","datePublished":"2026-07-25T08:51:20.319Z","dateUpdated":"2026-10-19T20:38:30.286Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-19T15:36:31.788Z"},"containers":{"cna":{"title":"tipc: fix out-of-bounds read in broadcast Gap ACK blocks","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ntipc: fix out-of-bounds read in broadcast Gap ACK blocks\n\nA broadcast PROTOCOL/STATE_MSG can carry a Gap ACK blocks record in its\ndata area. tipc_get_gap_ack_blks() only verifies that the record's len\nfield is self-consistent with its ugack_cnt/bgack_cnt counts\n(sz == struct_size(p, gacks, ugack_cnt + bgack_cnt)); it does not check\nthat the record actually fits in the message data area, msg_data_sz().\n\nThe unicast caller tipc_link_proto_rcv() bounds it (\"if (glen > dlen)\nbreak;\"), but the broadcast caller tipc_bcast_sync_rcv() discards the\nreturned size, so tipc_link_advance_transmq() copies the record off the\nreceive skb with an attacker-controlled count:\n\n\tthis_ga = kmemdup(ga, struct_size(ga, gacks, ga->bgack_cnt),\n\t\t\t  GFP_ATOMIC);\n\nA TIPC neighbour that negotiated TIPC_GAP_ACK_BLOCK triggers it with one\nordinary broadcast STATE_MSG (msg_bc_ack_invalid() clear), sized so its\ndata area is short, carrying a Gap ACK record with len = 0x400,\nbgack_cnt = 0xff and ugack_cnt = 0. len then equals\nstruct_size(p, gacks, 255), so the consistency check passes and ga is\nnon-NULL; kmemdup() reads struct_size(ga, gacks, 255) = 1024 bytes out\nof the much smaller skb:\n\n  BUG: KASAN: slab-out-of-bounds in kmemdup_noprof+0x48/0x60\n  Read of size 1024 at addr ffff0000c7030d38 by task poc864/69\n  Call trace:\n   kmemdup_noprof+0x48/0x60\n   tipc_link_advance_transmq+0x86c/0xb80\n   tipc_link_bc_ack_rcv+0x19c/0x1e0\n   tipc_bcast_sync_rcv+0x1c4/0x2c4\n   tipc_rcv+0x85c/0x1340\n   tipc_l2_rcv_msg+0xac/0x104\n  The buggy address belongs to the object at ffff0000c7030d00\n   which belongs to the cache skbuff_small_head of size 704\n  The buggy address is located 56 bytes inside of\n   allocated 704-byte region [ffff0000c7030d00, ffff0000c7030fc0)\n\nThe copied-out bytes are subsequently consumed as gap/ack values, but\nthe read is already out of bounds at the kmemdup() regardless of how\nthey are used.\n\nThe unicast STATE path drops such a message: \"if (glen > dlen) break;\"\nskips the rest of STATE_MSG handling and the skb is freed. Make the\nbroadcast path drop it too. tipc_bcast_sync_rcv() now bounds the record\nagainst msg_data_sz() and, when it does not fit, reports it back through\ntipc_node_bc_sync_rcv() to tipc_rcv() so the skb is discarded rather than\nprocessed. ga is not cleared on this path: ga == NULL already means\n\"legacy peer without Selective ACK\", a distinct legitimate state."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"d7626b5acff9227e2a65da636a53e09bdafdc0aa","status":"affected","lessThan":"055663d21dc4336f67933ab26bef3c5934be6324","versionType":"git"},{"version":"d7626b5acff9227e2a65da636a53e09bdafdc0aa","status":"affected","lessThan":"016f5995c37a5a2c45198308f830f244517d70b7","versionType":"git"},{"version":"d7626b5acff9227e2a65da636a53e09bdafdc0aa","status":"affected","lessThan":"74b45af86a767594ba52330cd440ea84e24d700d","versionType":"git"},{"version":"d7626b5acff9227e2a65da636a53e09bdafdc0aa","status":"affected","lessThan":"9a51115fcdc78687c8852bf93a1db3951dbb223b","versionType":"git"},{"version":"d7626b5acff9227e2a65da636a53e09bdafdc0aa","status":"affected","lessThan":"a21ed5064217cc33726da6c7ef1a520eba43aea1","versionType":"git"},{"version":"d7626b5acff9227e2a65da636a53e09bdafdc0aa","status":"affected","lessThan":"2de42e268174766cb2e2b90721afdfdff70e0d8d","versionType":"git"},{"version":"d7626b5acff9227e2a65da636a53e09bdafdc0aa","status":"affected","lessThan":"f333b6851bdf326fd2134133272dbbed0c94d921","versionType":"git"},{"version":"d7626b5acff9227e2a65da636a53e09bdafdc0aa","status":"affected","lessThan":"2b66974a1b6134a4bbc3bfed181f7418f688eb54","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/tipc/bcast.c","net/tipc/bcast.h","net/tipc/node.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.8","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.8","versionType":"semver"},{"version":"5.10.261","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.212","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.178","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.145","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.96","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.39","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.4","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/tipc/bcast.c","net/tipc/bcast.h","net/tipc/node.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/055663d21dc4336f67933ab26bef3c5934be6324"},{"url":"https://git.kernel.org/stable/c/016f5995c37a5a2c45198308f830f244517d70b7"},{"url":"https://git.kernel.org/stable/c/74b45af86a767594ba52330cd440ea84e24d700d"},{"url":"https://git.kernel.org/stable/c/9a51115fcdc78687c8852bf93a1db3951dbb223b"},{"url":"https://git.kernel.org/stable/c/a21ed5064217cc33726da6c7ef1a520eba43aea1"},{"url":"https://git.kernel.org/stable/c/2de42e268174766cb2e2b90721afdfdff70e0d8d"},{"url":"https://git.kernel.org/stable/c/f333b6851bdf326fd2134133272dbbed0c94d921"},{"url":"https://git.kernel.org/stable/c/2b66974a1b6134a4bbc3bfed181f7418f688eb54"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H","baseScore":9.1,"baseSeverity":"CRITICAL"},"scenarios":[{"lang":"en","value":"AV:N - TIPC packets can arrive through an IP/UDP bearer from a routable remote source, and the receive callback does not restrict packets to configured remote addresses. An attacker can also establish or spoof the required TIPC neighbour state without credentials.\nAC:L - The attacker controls capability advertisement, link establishment, broadcast synchronization, and the malformed STATE message; one packet then reliably performs the out-of-bounds copy without a race or uncontrollable condition.\nPR:N - The packet-receive path performs no capability or user-credential check, and TIPC discovery and link negotiation are unauthenticated when optional cryptographic keys are not configured. The vulnerable broadcast processing also precedes normal STATE-session validation.\nUI:N - No victim action is required after the TIPC bearer is active; receipt of the crafted STATE message directly invokes the vulnerable code.\nS:U - The vulnerability compromises availability and potentially confidentiality within the receiving kernel's existing security authority, without crossing a VM, IOMMU, or comparable scope boundary.\nC:H - The attacker-controlled count makes the kernel copy up to 1,024 bytes from a much smaller skb, incorporating substantial adjacent slab contents rather than a strictly bounded few-byte read.\nI:N - The defect performs an out-of-bounds read into a correctly sized new allocation; investigation found no out-of-bounds write, arbitrary-write primitive, or control-flow corruption.\nA:H - The demonstrated 1,024-byte slab-out-of-bounds access produces a KASAN BUG and can panic or fault hardened kernels, and an unauthenticated attacker can trigger it repeatedly."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-17T04:55:54.043Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.8","versionEndExcluding":"5.10.261"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.8","versionEndExcluding":"5.15.212"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.8","versionEndExcluding":"6.1.178"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.8","versionEndExcluding":"6.6.145"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.8","versionEndExcluding":"6.12.96"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.8","versionEndExcluding":"6.18.39"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.8","versionEndExcluding":"7.1.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.8","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-64450","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"version":"2.0.3","timestamp":"2026-10-16T15:41:04.841993Z"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-125","lang":"en","type":"CWE","description":"CWE-125 Out-of-bounds Read"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-19T20:38:30.286Z"}}]}}}