CVE-2026-74479

Received Received - Intake

Use-After-Free in Linux Kernel pktgen

Publication date: 2026-08-15

Last updated on: 2026-08-23

Assigner: kernel.org

Description

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.

CVSS Scores

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Meta Information

Published

2026-08-15

Last Modified

2026-08-23

Generated

2026-09-04

AI Q&A

2026-08-15

EPSS Evaluated

2026-09-03

NVD

CVE-2026-74479

EUVD

EUVD-2026-59672

Affected Vendors & Products

Vendor	Product	Version / Range
linux	linux_kernel	*

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This is a use-after-free vulnerability in the Linux kernel's pktgen module. It occurs when a proc entry is removed while another thread still holds a reference to it. The race condition happens between renaming a pktgen device and removing it, leading to a kernel slab-use-after-free error when proc_remove() is called on an already freed entry.

Detection Guidance

This vulnerability is specific to the Linux kernel's pktgen module and may not have direct detection commands. Monitor kernel logs for KASAN reports or slab-use-after-free errors related to proc_remove or pktgen. Check if your kernel version includes the fix by verifying the patch is applied.

Impact Analysis

This vulnerability could cause kernel crashes or instability on systems running vulnerable Linux kernel versions with pktgen enabled. An attacker with local access might exploit this to trigger denial-of-service conditions or potentially escalate privileges, though no public exploits are currently known.

Compliance Impact

This vulnerability is a use-after-free flaw in the Linux kernel's pktgen module, which could lead to memory corruption or crashes. It does not directly impact data privacy or security controls required by standards like GDPR or HIPAA. Compliance risks would arise only if exploitation caused system instability or unauthorized access, which is not described in the provided context.

Mitigation Strategies

Apply the latest kernel patches or updates that include the fix for CVE-2026-74479. If immediate patching is not possible, disable the pktgen module by unloading it with 'rmmod pktgen' or blacklisting it. Monitor system logs for signs of exploitation or crashes.

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