CVE-2026-74479 (GCVE-0-2026-74479)
Vulnerability from cvelistv5
Published
2026-08-15 12:27
Modified
2026-08-23 12:47
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
net: pktgen: fix proc entry use-after-free
pktgen_change_name() replaces pkt_dev->entry while holding t->if_lock.
pktgen_remove_device() removes the same entry before
_rem_dev_from_if_list() takes that lock.
This allows the following interleaving:
CPU 0 (NETDEV_CHANGENAME) CPU 1 (kpktgend)
if_lock(t)
proc_remove(pkt_dev->entry)
proc_remove(pkt_dev->entry)
pkt_dev->entry = proc_create_data(...)
if_unlock(t)
The kthread can pass the stale proc_dir_entry to proc_remove() after the
rename path has freed it. A reproducer with a widened race window reports:
BUG: KASAN: slab-use-after-free in proc_remove+0x78/0x80
Read of size 8 at addr ffff8881478fea70 by task kpktgend_0/67
Call Trace:
proc_remove+0x78/0x80
pktgen_remove_device.isra.0+0x11c/0x4c0
pktgen_thread_worker+0x1214/0x6bc0
kthread+0x2c6/0x3b0
Allocated by task 95:
__proc_create+0x204/0x790
proc_create_data+0x72/0xe0
pktgen_thread_write+0xd61/0x1510
Freed by task 28:
kmem_cache_free+0xcb/0x3d0
proc_free_inode+0x5b/0x80
rcu_core+0x50a/0x1850
The buggy address belongs to the object at ffff8881478fea00
which belongs to the cache proc_dir_entry of size 192
Move proc_remove() into the if_lock-protected list removal helper. Keep it
before list_del_rcu() to preserve the ordering required by add_device().
The rename path must then finish replacing the entry before removal, or
it observes that the device is no longer on the list.
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: 39df232f1a9ba48d41c68ee7d4046756e709cf91 Version: 39df232f1a9ba48d41c68ee7d4046756e709cf91 Version: 39df232f1a9ba48d41c68ee7d4046756e709cf91 Version: 39df232f1a9ba48d41c68ee7d4046756e709cf91 Version: 39df232f1a9ba48d41c68ee7d4046756e709cf91 Version: 39df232f1a9ba48d41c68ee7d4046756e709cf91 Version: 39df232f1a9ba48d41c68ee7d4046756e709cf91 Version: 39df232f1a9ba48d41c68ee7d4046756e709cf91 |
||
{
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{
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{
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"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: pktgen: fix proc entry use-after-free\n\npktgen_change_name() replaces pkt_dev-\u003eentry while holding t-\u003eif_lock.\npktgen_remove_device() removes the same entry before\n_rem_dev_from_if_list() takes that lock.\n\nThis allows the following interleaving:\n\n CPU 0 (NETDEV_CHANGENAME) CPU 1 (kpktgend)\n if_lock(t)\n proc_remove(pkt_dev-\u003eentry)\n proc_remove(pkt_dev-\u003eentry)\n pkt_dev-\u003eentry = proc_create_data(...)\n if_unlock(t)\n\nThe kthread can pass the stale proc_dir_entry to proc_remove() after the\nrename path has freed it. A reproducer with a widened race window reports:\n\n BUG: KASAN: slab-use-after-free in proc_remove+0x78/0x80\n Read of size 8 at addr ffff8881478fea70 by task kpktgend_0/67\n Call Trace:\n proc_remove+0x78/0x80\n pktgen_remove_device.isra.0+0x11c/0x4c0\n pktgen_thread_worker+0x1214/0x6bc0\n kthread+0x2c6/0x3b0\n Allocated by task 95:\n __proc_create+0x204/0x790\n proc_create_data+0x72/0xe0\n pktgen_thread_write+0xd61/0x1510\n Freed by task 28:\n kmem_cache_free+0xcb/0x3d0\n proc_free_inode+0x5b/0x80\n rcu_core+0x50a/0x1850\n The buggy address belongs to the object at ffff8881478fea00\n which belongs to the cache proc_dir_entry of size 192\n\nMove proc_remove() into the if_lock-protected list removal helper. Keep it\nbefore list_del_rcu() to preserve the ordering required by add_device().\nThe rename path must then finish replacing the entry before removal, or\nit observes that the device is no longer on the list."
}
],
"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 - Exploitation requires local access to /proc/net/pktgen procfs writes and a SIOCSIFNAME/ip-link rename of a pktgen-bound netdev; pktgen is configured only via local proc and ioctl paths, not via remote network packets.\nAC:L - The UAF is a race between pktgen_change_name() on NETDEV_CHANGENAME and pktgen_remove_device() in kpktgend; an attacker controls both sides concurrently via rem_device_all/unregister and interface rename, so success does not depend on uncontrollable timing.\nPR:L - Triggering rename needs ns_capable(CAP_NET_ADMIN) and pktgen proc writes are mode 0600; CAP_NET_ADMIN is obtainable by an unprivileged user via user/network namespaces (unshare -Urn), so real init-namespace root is not required.\nUI:N - No victim interaction is required; the attacker drives pktgen device add/remove and netdev rename/unregister directly through local proc writes and netlink/ioctl without needing another user to act.\nS:U - Impact is kernel slab corruption and potential privilege escalation within the same kernel security domain; it does not inherently cross VM, container, or IOMMU boundaries without additional unrelated primitives.\nC:H - The bug is a slab use-after-free of a proc_dir_entry in proc_remove(); KASAN shows reads of freed 192-byte objects, and UAF on proc metadata can be turned into arbitrary kernel memory disclosure via heap grooming.\nI:H - Corrupting or reusing the freed proc_dir_entry during proc_remove()/procfs teardown can enable attacker-controlled writes and control-flow hijack in kernel context, not merely a benign NULL dereference crash.\nA:H - Concurrent rename and removal causes proc_remove() to dereference a freed proc_dir_entry, producing KASAN slab-use-after-free and kernel oops/panic; even without full exploit development, the UAF reliably threatens system availability."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-23T12:47:23.408Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/82ed3db9269cb61e3c15bad2f6e221efce90e1e0"
},
{
"url": "https://git.kernel.org/stable/c/d1cc9797cf8f7aeb87e7ad01b748c6a960a819e4"
},
{
"url": "https://git.kernel.org/stable/c/7991c7cff8b8622cddb3d8dee07dbe74aa4cbec4"
},
{
"url": "https://git.kernel.org/stable/c/577443530cb592d5782a1f79847411a9363a65c8"
},
{
"url": "https://git.kernel.org/stable/c/f85a58340b91f225de3299dfa782c6414098077c"
},
{
"url": "https://git.kernel.org/stable/c/4ef801b838d85c0ea5852c50667f7344ce3b6cd0"
},
{
"url": "https://git.kernel.org/stable/c/b006a5404470bd3eb2aa0425fc447183032047ef"
},
{
"url": "https://git.kernel.org/stable/c/817ff6efdb7f484ea547218e11e17d8e43daa3b4"
}
],
"title": "net: pktgen: fix proc entry use-after-free",
"x_generator": {
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}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-74479",
"datePublished": "2026-08-15T12:27:13.172Z",
"dateReserved": "2026-08-15T05:44:03.904Z",
"dateUpdated": "2026-08-23T12:47:23.408Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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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.
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