CVE-2026-64450 (GCVE-0-2026-64450)
Vulnerability from cvelistv5
Published
2026-07-25 08:51
Modified
2026-10-19 20:38
Severity ?
9.1 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: tipc: fix out-of-bounds read in broadcast Gap ACK blocks A broadcast PROTOCOL/STATE_MSG can carry a Gap ACK blocks record in its data area. tipc_get_gap_ack_blks() only verifies that the record's len field is self-consistent with its ugack_cnt/bgack_cnt counts (sz == struct_size(p, gacks, ugack_cnt + bgack_cnt)); it does not check that the record actually fits in the message data area, msg_data_sz(). The unicast caller tipc_link_proto_rcv() bounds it ("if (glen > dlen) break;"), but the broadcast caller tipc_bcast_sync_rcv() discards the returned size, so tipc_link_advance_transmq() copies the record off the receive skb with an attacker-controlled count: this_ga = kmemdup(ga, struct_size(ga, gacks, ga->bgack_cnt), GFP_ATOMIC); A TIPC neighbour that negotiated TIPC_GAP_ACK_BLOCK triggers it with one ordinary broadcast STATE_MSG (msg_bc_ack_invalid() clear), sized so its data area is short, carrying a Gap ACK record with len = 0x400, bgack_cnt = 0xff and ugack_cnt = 0. len then equals struct_size(p, gacks, 255), so the consistency check passes and ga is non-NULL; kmemdup() reads struct_size(ga, gacks, 255) = 1024 bytes out of the much smaller skb: BUG: KASAN: slab-out-of-bounds in kmemdup_noprof+0x48/0x60 Read of size 1024 at addr ffff0000c7030d38 by task poc864/69 Call trace: kmemdup_noprof+0x48/0x60 tipc_link_advance_transmq+0x86c/0xb80 tipc_link_bc_ack_rcv+0x19c/0x1e0 tipc_bcast_sync_rcv+0x1c4/0x2c4 tipc_rcv+0x85c/0x1340 tipc_l2_rcv_msg+0xac/0x104 The buggy address belongs to the object at ffff0000c7030d00 which belongs to the cache skbuff_small_head of size 704 The buggy address is located 56 bytes inside of allocated 704-byte region [ffff0000c7030d00, ffff0000c7030fc0) The copied-out bytes are subsequently consumed as gap/ack values, but the read is already out of bounds at the kmemdup() regardless of how they are used. The unicast STATE path drops such a message: "if (glen > dlen) break;" skips the rest of STATE_MSG handling and the skb is freed. Make the broadcast path drop it too. tipc_bcast_sync_rcv() now bounds the record against msg_data_sz() and, when it does not fit, reports it back through tipc_node_bc_sync_rcv() to tipc_rcv() so the skb is discarded rather than processed. ga is not cleared on this path: ga == NULL already means "legacy peer without Selective ACK", a distinct legitimate state.
References
Impacted products
Vendor Product Version
Linux Linux Version: d7626b5acff9227e2a65da636a53e09bdafdc0aa
Version: d7626b5acff9227e2a65da636a53e09bdafdc0aa
Version: d7626b5acff9227e2a65da636a53e09bdafdc0aa
Version: d7626b5acff9227e2a65da636a53e09bdafdc0aa
Version: d7626b5acff9227e2a65da636a53e09bdafdc0aa
Version: d7626b5acff9227e2a65da636a53e09bdafdc0aa
Version: d7626b5acff9227e2a65da636a53e09bdafdc0aa
Version: d7626b5acff9227e2a65da636a53e09bdafdc0aa
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          "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\u0027s 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 \u003e 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-\u003ebgack_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 \u003e 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."
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            "version": "3.1"
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              "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\u0027s 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."
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        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/016f5995c37a5a2c45198308f830f244517d70b7"
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        {
          "url": "https://git.kernel.org/stable/c/2b66974a1b6134a4bbc3bfed181f7418f688eb54"
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      "title": "tipc: fix out-of-bounds read in broadcast Gap ACK blocks",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64450",
    "datePublished": "2026-07-25T08:51:20.319Z",
    "dateReserved": "2026-07-19T15:36:31.788Z",
    "dateUpdated": "2026-10-19T20:38:30.286Z",
    "state": "PUBLISHED"
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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\u0027s 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 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\"a21ed5064217cc33726da6c7ef1a520eba43aea1\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"d7626b5acff9227e2a65da636a53e09bdafdc0aa\", \"lessThan\": \"2de42e268174766cb2e2b90721afdfdff70e0d8d\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"d7626b5acff9227e2a65da636a53e09bdafdc0aa\", \"lessThan\": \"f333b6851bdf326fd2134133272dbbed0c94d921\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"d7626b5acff9227e2a65da636a53e09bdafdc0aa\", \"lessThan\": \"2b66974a1b6134a4bbc3bfed181f7418f688eb54\", \"versionType\": \"git\"}], \"programFiles\": [\"net/tipc/bcast.c\", \"net/tipc/bcast.h\", \"net/tipc/node.c\"], \"defaultStatus\": \"unaffected\"}, {\"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\", \"vendor\": \"Linux\", \"product\": \"Linux\", \"versions\": [{\"status\": \"affected\", \"version\": \"5.8\"}, {\"status\": \"unaffected\", \"version\": \"0\", \"lessThan\": \"5.8\", \"versionType\": \"semver\"}, {\"status\": \"unaffected\", \"version\": \"5.10.261\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"5.10.*\"}, {\"status\": \"unaffected\", \"version\": \"5.15.212\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"5.15.*\"}, {\"status\": \"unaffected\", \"version\": \"6.1.178\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.1.*\"}, {\"status\": \"unaffected\", \"version\": \"6.6.145\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.6.*\"}, {\"status\": \"unaffected\", \"version\": \"6.12.96\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.12.*\"}, {\"status\": \"unaffected\", \"version\": \"6.18.39\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.18.*\"}, {\"status\": \"unaffected\", \"version\": \"7.1.4\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"7.1.*\"}, {\"status\": \"unaffected\", \"version\": \"7.2\", \"versionType\": \"original_commit_for_fix\", \"lessThanOrEqual\": \"*\"}], \"programFiles\": [\"net/tipc/bcast.c\", \"net/tipc/bcast.h\", \"net/tipc/node.c\"], \"defaultStatus\": \"affected\"}], \"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\"}], \"x_generator\": {\"engine\": \"bippy-1.2.0\"}, \"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\u0027s 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 \u003e 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-\u003ebgack_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 \u003e 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.\"}], \"cpeApplicability\": [{\"nodes\": [{\"negate\": false, \"cpeMatch\": [{\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"5.10.261\", \"versionStartIncluding\": \"5.8\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"5.15.212\", \"versionStartIncluding\": \"5.8\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.1.178\", \"versionStartIncluding\": \"5.8\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.6.145\", \"versionStartIncluding\": \"5.8\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.12.96\", \"versionStartIncluding\": \"5.8\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.18.39\", \"versionStartIncluding\": \"5.8\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"7.1.4\", \"versionStartIncluding\": \"5.8\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"7.2\", \"versionStartIncluding\": \"5.8\"}], \"operator\": \"OR\"}]}], \"providerMetadata\": {\"orgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"shortName\": \"Linux\", \"dateUpdated\": \"2026-08-17T04:55:54.043Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-64450\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-10-19T20:38:30.286Z\", \"dateReserved\": \"2026-07-19T15:36:31.788Z\", \"assignerOrgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"datePublished\": \"2026-07-25T08:51:20.319Z\", \"assignerShortName\": \"Linux\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}


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