CVE-2026-74609 (GCVE-0-2026-74609)
Vulnerability from cvelistv5
Published
2026-08-22 15:31
Modified
2026-08-25 05:40
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
tipc: read le->link under the node lock in tipc_node_link_down()
tipc_node_link_down() caches the link pointer before taking n->lock:
struct tipc_link *l = le->link; /* unlocked */
if (!l)
return;
tipc_node_write_lock(n);
if (!tipc_link_is_establishing(l)) { /* deref l */
...
tipc_link_reset(l); /* write into l */
if (delete) {
kfree(l);
le->link = NULL;
The delete=true caller frees that very object under n->lock, so the lock
does not protect the cached pointer against it:
- CPU A, delete=false: tipc_rcv() on TIPC_LINK_DOWN_EVT, or the link
supervision timer via tipc_node_timeout(), reads l unlocked and then
dereferences it under n->lock;
- CPU B, delete=true: netlink TIPC_NL_BEARER_DISABLE -> bearer_disable()
-> tipc_node_delete_links() -> tipc_node_link_down(n, bearer_id, true)
-> kfree(l).
The link is freed with plain kfree(), not kfree_rcu(), and for UDP bearers
disable_media() only schedules the asynchronous cleanup_bearer() work, so
its synchronize_net() runs after the links are already gone. An in-flight
CPU A that has read l therefore dereferences freed memory once B frees it:
a use-after-free read in tipc_link_is_establishing(), and a use-after-free
write via tipc_link_reset() on the establishing branch.
The following trace was captured on 7.2.0-rc5-00284-gaf39eb111ce6:
BUG: KASAN: slab-use-after-free in tipc_link_is_establishing (net/tipc/link.c:285)
Read of size 4 at addr ffff88802e2aa068 by task swapper/2/0
tipc_link_is_establishing (net/tipc/link.c:285)
tipc_node_link_down (net/tipc/node.c:1076)
tipc_node_timeout (net/tipc/node.c:843)
Allocated by task 9549:
tipc_link_create (net/tipc/link.c:490)
tipc_node_check_dest (net/tipc/node.c:1279)
tipc_disc_rcv (net/tipc/discover.c:252)
tipc_udp_recv (net/tipc/udp_media.c:389)
Freed by task 9549:
tipc_node_link_down (net/tipc/node.c:1084)
tipc_node_delete_links (net/tipc/node.c:1320)
bearer_disable (net/tipc/bearer.c:414)
__tipc_nl_bearer_disable (net/tipc/bearer.c:992)
Move the le->link read inside tipc_node_write_lock(), so it is serialised
against the kfree() in the delete path. A racing teardown now either has
not run yet, and we see a valid link, or has already run, and we see NULL.
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: 73f646cec35477b5099d7e952297cb9e1855be45 Version: 73f646cec35477b5099d7e952297cb9e1855be45 Version: 73f646cec35477b5099d7e952297cb9e1855be45 Version: 73f646cec35477b5099d7e952297cb9e1855be45 Version: 73f646cec35477b5099d7e952297cb9e1855be45 Version: 73f646cec35477b5099d7e952297cb9e1855be45 Version: 73f646cec35477b5099d7e952297cb9e1855be45 Version: 73f646cec35477b5099d7e952297cb9e1855be45 |
||
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/tipc/node.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "2be741ad565c610871a6a95062c12c39da7168fd",
"status": "affected",
"version": "73f646cec35477b5099d7e952297cb9e1855be45",
"versionType": "git"
},
{
"lessThan": "69d209461c110388710e483a130caf051e4fd09a",
"status": "affected",
"version": "73f646cec35477b5099d7e952297cb9e1855be45",
"versionType": "git"
},
{
"lessThan": "de017c22135f545ca4e65d1eada22887b64958eb",
"status": "affected",
"version": "73f646cec35477b5099d7e952297cb9e1855be45",
"versionType": "git"
},
{
"lessThan": "47ba70891b10b2feb52462086b7fcd2ad75d3ce3",
"status": "affected",
"version": "73f646cec35477b5099d7e952297cb9e1855be45",
"versionType": "git"
},
{
"lessThan": "a714d62513befef37f71f4ae89bb1fe173b65f2e",
"status": "affected",
"version": "73f646cec35477b5099d7e952297cb9e1855be45",
"versionType": "git"
},
{
"lessThan": "c3f2347a47754eac690967cfd82cb6d559817b07",
"status": "affected",
"version": "73f646cec35477b5099d7e952297cb9e1855be45",
"versionType": "git"
},
{
"lessThan": "5558a8312452ddb21eff22b1cbd84302ad951944",
"status": "affected",
"version": "73f646cec35477b5099d7e952297cb9e1855be45",
"versionType": "git"
},
{
"lessThan": "cba9ccb47e9fa4cc77692fb896cc5ab57a667882",
"status": "affected",
"version": "73f646cec35477b5099d7e952297cb9e1855be45",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"net/tipc/node.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "4.4"
},
{
"lessThan": "4.4",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
"version": "5.10.265",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"version": "5.15.216",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.183",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.152",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.104",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.45",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
"version": "7.1.9",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "5.10.265",
"versionStartIncluding": "4.4",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "5.15.216",
"versionStartIncluding": "4.4",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.1.183",
"versionStartIncluding": "4.4",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.6.152",
"versionStartIncluding": "4.4",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.12.104",
"versionStartIncluding": "4.4",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18.45",
"versionStartIncluding": "4.4",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.1.9",
"versionStartIncluding": "4.4",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.2",
"versionStartIncluding": "4.4",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntipc: read le-\u003elink under the node lock in tipc_node_link_down()\n\ntipc_node_link_down() caches the link pointer before taking n-\u003elock:\n\n\tstruct tipc_link *l = le-\u003elink;\t\t/* unlocked */\n\n\tif (!l)\n\t\treturn;\n\ttipc_node_write_lock(n);\n\tif (!tipc_link_is_establishing(l)) {\t/* deref l */\n\t...\n\t\ttipc_link_reset(l);\t\t/* write into l */\n\tif (delete) {\n\t\tkfree(l);\n\t\tle-\u003elink = NULL;\n\nThe delete=true caller frees that very object under n-\u003elock, so the lock\ndoes not protect the cached pointer against it:\n\n - CPU A, delete=false: tipc_rcv() on TIPC_LINK_DOWN_EVT, or the link\n supervision timer via tipc_node_timeout(), reads l unlocked and then\n dereferences it under n-\u003elock;\n - CPU B, delete=true: netlink TIPC_NL_BEARER_DISABLE -\u003e bearer_disable()\n -\u003e tipc_node_delete_links() -\u003e tipc_node_link_down(n, bearer_id, true)\n -\u003e kfree(l).\n\nThe link is freed with plain kfree(), not kfree_rcu(), and for UDP bearers\ndisable_media() only schedules the asynchronous cleanup_bearer() work, so\nits synchronize_net() runs after the links are already gone. An in-flight\nCPU A that has read l therefore dereferences freed memory once B frees it:\na use-after-free read in tipc_link_is_establishing(), and a use-after-free\nwrite via tipc_link_reset() on the establishing branch.\n\nThe following trace was captured on 7.2.0-rc5-00284-gaf39eb111ce6:\n\n BUG: KASAN: slab-use-after-free in tipc_link_is_establishing (net/tipc/link.c:285)\n Read of size 4 at addr ffff88802e2aa068 by task swapper/2/0\n tipc_link_is_establishing (net/tipc/link.c:285)\n tipc_node_link_down (net/tipc/node.c:1076)\n tipc_node_timeout (net/tipc/node.c:843)\n Allocated by task 9549:\n tipc_link_create (net/tipc/link.c:490)\n tipc_node_check_dest (net/tipc/node.c:1279)\n tipc_disc_rcv (net/tipc/discover.c:252)\n tipc_udp_recv (net/tipc/udp_media.c:389)\n Freed by task 9549:\n tipc_node_link_down (net/tipc/node.c:1084)\n tipc_node_delete_links (net/tipc/node.c:1320)\n bearer_disable (net/tipc/bearer.c:414)\n __tipc_nl_bearer_disable (net/tipc/bearer.c:992)\n\nMove the le-\u003elink read inside tipc_node_write_lock(), so it is serialised\nagainst the kfree() in the delete path. A racing teardown now either has\nnot run yet, and we see a valid link, or has already run, and we see NULL."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 7.8,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:L - The UAF race requires the delete=true path (kfree) via TIPC_NL_BEARER_DISABLE/bearer_disable() or netns teardown, reachable only through local RTNL/genlink with CAP_NET_ADMIN; remote tipc_rcv() packets alone cannot free links and complete the race.\nAC:L - An attacker with CAP_NET_ADMIN controls both CPUs by scripting bearer disable/netns teardown while concurrently driving link-down events via TIPC traffic or link supervision timers; KASAN reproduced this reliably without uncontrollable victim timing.\nPR:L - Bearer disable and link deletion require CAP_NET_ADMIN (GENL_UNS_ADMIN_PERM on TIPC_NL_BEARER_DISABLE); tipc_genl_family is netns-aware, so unprivileged users obtain effective net-admin via user/network namespaces (unshare -Urn).\nUI:N - No victim interaction is required; the attacker scripts bearer teardown and concurrent TIPC link activity from their own processes without needing another user to mount, open files, or perform administrative actions.\nS:U - Slab UAF corrupts host kernel heap memory within the same kernel security authority; impact is kernel crash or local privilege escalation, not a VM, IOMMU, or cross-container sandbox boundary escape.\nC:H - Slab use-after-free read in tipc_link_is_establishing() dereferences freed tipc_link objects (KASAN-confirmed), enabling disclosure of freed kernel memory and supporting further heap exploitation primitives.\nI:H - On the establishing branch tipc_link_reset() performs multiple writes into the freed tipc_link structure, corrupting kernel heap metadata and adjacent objects in ways exploitable for arbitrary write and control-flow hijacking.\nA:H - KASAN-confirmed slab-use-after-free in tipc_node_link_down() causes kernel oops/panic (observed on swapper during tipc_node_timeout), and the race can be retriggered during bearer teardown loops for reliable denial of service."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-25T05:40:34.778Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/2be741ad565c610871a6a95062c12c39da7168fd"
},
{
"url": "https://git.kernel.org/stable/c/69d209461c110388710e483a130caf051e4fd09a"
},
{
"url": "https://git.kernel.org/stable/c/de017c22135f545ca4e65d1eada22887b64958eb"
},
{
"url": "https://git.kernel.org/stable/c/47ba70891b10b2feb52462086b7fcd2ad75d3ce3"
},
{
"url": "https://git.kernel.org/stable/c/a714d62513befef37f71f4ae89bb1fe173b65f2e"
},
{
"url": "https://git.kernel.org/stable/c/c3f2347a47754eac690967cfd82cb6d559817b07"
},
{
"url": "https://git.kernel.org/stable/c/5558a8312452ddb21eff22b1cbd84302ad951944"
},
{
"url": "https://git.kernel.org/stable/c/cba9ccb47e9fa4cc77692fb896cc5ab57a667882"
}
],
"title": "tipc: read le-\u003elink under the node lock in tipc_node_link_down()",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-74609",
"datePublished": "2026-08-22T15:31:56.054Z",
"dateReserved": "2026-08-15T05:44:03.920Z",
"dateUpdated": "2026-08-25T05:40:34.778Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
Loading…
Loading…
Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
Loading…
Loading…