FKIE_CVE-2026-64450
Vulnerability from fkie_nvd - Published: 2026-07-25 10:17 - Updated: 2026-07-27 05:16
Severity
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 |
|---|
{
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/tipc/bcast.c",
"net/tipc/bcast.h",
"net/tipc/node.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "055663d21dc4336f67933ab26bef3c5934be6324",
"status": "affected",
"version": "d7626b5acff9227e2a65da636a53e09bdafdc0aa",
"versionType": "git"
},
{
"lessThan": "016f5995c37a5a2c45198308f830f244517d70b7",
"status": "affected",
"version": "d7626b5acff9227e2a65da636a53e09bdafdc0aa",
"versionType": "git"
},
{
"lessThan": "74b45af86a767594ba52330cd440ea84e24d700d",
"status": "affected",
"version": "d7626b5acff9227e2a65da636a53e09bdafdc0aa",
"versionType": "git"
},
{
"lessThan": "9a51115fcdc78687c8852bf93a1db3951dbb223b",
"status": "affected",
"version": "d7626b5acff9227e2a65da636a53e09bdafdc0aa",
"versionType": "git"
},
{
"lessThan": "a21ed5064217cc33726da6c7ef1a520eba43aea1",
"status": "affected",
"version": "d7626b5acff9227e2a65da636a53e09bdafdc0aa",
"versionType": "git"
},
{
"lessThan": "2de42e268174766cb2e2b90721afdfdff70e0d8d",
"status": "affected",
"version": "d7626b5acff9227e2a65da636a53e09bdafdc0aa",
"versionType": "git"
},
{
"lessThan": "f333b6851bdf326fd2134133272dbbed0c94d921",
"status": "affected",
"version": "d7626b5acff9227e2a65da636a53e09bdafdc0aa",
"versionType": "git"
},
{
"lessThan": "2b66974a1b6134a4bbc3bfed181f7418f688eb54",
"status": "affected",
"version": "d7626b5acff9227e2a65da636a53e09bdafdc0aa",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"net/tipc/bcast.c",
"net/tipc/bcast.h",
"net/tipc/node.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "5.8"
},
{
"lessThan": "5.8",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
"version": "5.10.261",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"version": "5.15.212",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.178",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.145",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.96",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.39",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
"version": "7.1.4",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2-rc2",
"versionType": "original_commit_for_fix"
}
]
}
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"cveTags": [],
"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."
}
],
"id": "CVE-2026-64450",
"lastModified": "2026-07-27T05:16:51.920",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "HIGH",
"baseScore": 9.1,
"baseSeverity": "CRITICAL",
"confidentialityImpact": "HIGH",
"integrityImpact": "NONE",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H",
"version": "3.1"
},
"exploitabilityScore": 3.9,
"impactScore": 5.2,
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary"
}
]
},
"published": "2026-07-25T10:17:29.850",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/016f5995c37a5a2c45198308f830f244517d70b7"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/055663d21dc4336f67933ab26bef3c5934be6324"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/2b66974a1b6134a4bbc3bfed181f7418f688eb54"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/2de42e268174766cb2e2b90721afdfdff70e0d8d"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/74b45af86a767594ba52330cd440ea84e24d700d"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/9a51115fcdc78687c8852bf93a1db3951dbb223b"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/a21ed5064217cc33726da6c7ef1a520eba43aea1"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/f333b6851bdf326fd2134133272dbbed0c94d921"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Received"
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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