CVE-2022-49390
Published: 26 February 2025
Summary
CVE-2022-49390 is a high-severity Use After Free (CWE-416) vulnerability in Linux Linux Kernel. Its CVSS base score is 7.8 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 2.2th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 SI-2 (Flaw Remediation) and RA-5 (Vulnerability Monitoring and Scanning).
Deeper analysis
CVE-2022-49390 is a use-after-free (UAF) vulnerability in the Linux kernel's MACsec (Media Access Control Security) implementation within drivers/net/macsec.c. The issue arises when a new MACsec device is created without obtaining a reference to the underlying real_dev, failing to ensure that real_dev remains valid after the MACsec device. This leads to a UAF when real_dev is freed prematurely, as detected by KASAN in functions like macsec_get_iflink during operations such as dev_get_iflink and linkwatch processing. The vulnerability is classified under CWE-416 with a CVSS v3.1 base score of 7.8 (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H).
A local attacker with low privileges can exploit this vulnerability due to its low attack complexity and lack of user interaction requirements. Exploitation involves scenarios where the real_dev is unregistered or freed out-of-order, such as after commits like faab39f63c1f ("net: allow out-of-order netdev unregistration") and e5f80fcf869a ("ipv6: give an IPv6 dev to blackhole_netdev"). Successful exploitation could result in high-impact confidentiality, integrity, and availability violations, potentially allowing arbitrary code execution, data corruption, or system crashes via the UAF in MACsec-related netdevice operations.
Kernel patch commits address the issue by adding dev_hold_track() in macsec_dev_init() to acquire a reference to real_dev and dev_put_track() in macsec_free_netdev() to release it properly, ensuring reference counting prevents premature freeing. Relevant stable kernel patches are available at https://git.kernel.org/stable/c/196a888ca6571deb344468e1d7138e3273206335, https://git.kernel.org/stable/c/78933cbc143b82d02330e00900d2fd08f2682f4e, and https://git.kernel.org/stable/c/d130282179aa6051449ac8f8df1115769998a665.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2022-54839
Vulnerability details
In the Linux kernel, the following vulnerability has been resolved: macsec: fix UAF bug for real_dev Create a new macsec device but not get reference to real_dev. That can not ensure that real_dev is freed after macsec. That will trigger…
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the UAF bug for real_dev as following: ================================================================== BUG: KASAN: use-after-free in macsec_get_iflink+0x5f/0x70 drivers/net/macsec.c:3662 Call Trace: ... macsec_get_iflink+0x5f/0x70 drivers/net/macsec.c:3662 dev_get_iflink+0x73/0xe0 net/core/dev.c:637 default_operstate net/core/link_watch.c:42 [inline] rfc2863_policy+0x233/0x2d0 net/core/link_watch.c:54 linkwatch_do_dev+0x2a/0x150 net/core/link_watch.c:161 Allocated by task 22209: ... alloc_netdev_mqs+0x98/0x1100 net/core/dev.c:10549 rtnl_create_link+0x9d7/0xc00 net/core/rtnetlink.c:3235 veth_newlink+0x20e/0xa90 drivers/net/veth.c:1748 Freed by task 8: ... kfree+0xd6/0x4d0 mm/slub.c:4552 kvfree+0x42/0x50 mm/util.c:615 device_release+0x9f/0x240 drivers/base/core.c:2229 kobject_cleanup lib/kobject.c:673 [inline] kobject_release lib/kobject.c:704 [inline] kref_put include/linux/kref.h:65 [inline] kobject_put+0x1c8/0x540 lib/kobject.c:721 netdev_run_todo+0x72e/0x10b0 net/core/dev.c:10327 After commit faab39f63c1f ("net: allow out-of-order netdev unregistration") and commit e5f80fcf869a ("ipv6: give an IPv6 dev to blackhole_netdev"), we can add dev_hold_track() in macsec_dev_init() and dev_put_track() in macsec_free_netdev() to fix the problem.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Local kernel UAF in MACsec netdevice handling directly enables privilege escalation via arbitrary code execution from low-privileged context.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Remediating the Linux kernel flaw via stable patches directly resolves the MACsec UAF by implementing proper reference counting on real_dev.
Kernel memory protection mechanisms like KASLR and SMEP mitigate exploitation of the MACsec real_dev UAF by complicating unauthorized memory access.
Vulnerability scanning identifies affected Linux kernel versions vulnerable to CVE-2022-49390, enabling prioritization of remediation.