CVE-2026-23209

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Source
https://cve.org/CVERecord?id=CVE-2026-23209
Import Source
https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-23209.json
JSON Data
https://api.test.osv.dev/v1/vulns/CVE-2026-23209
Downstream
Related
Published
2026-02-14T16:27:31Z
Modified
2026-08-12T03:30:34Z
Severity
  • 7.8 (High) CVSS_V3 - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H CVSS Calculator
Summary
macvlan: fix error recovery in macvlan_common_newlink()
Details

In the Linux kernel, the following vulnerability has been resolved:

macvlan: fix error recovery in macvlan_common_newlink()

valis provided a nice repro to crash the kernel:

ip link add p1 type veth peer p2 ip link set address 00:00:00:00:00:20 dev p1 ip link set up dev p1 ip link set up dev p2

ip link add mv0 link p2 type macvlan mode source ip link add invalid% link p2 type macvlan mode source macaddr add 00:00:00:00:00:20

ping -c1 -I p1 1.2.3.4

He also gave a very detailed analysis:

The issue is triggered when a new macvlan link is created with MACVLAN_MODE_SOURCE mode and MACVLAN_MACADDR_ADD (or MACVLAN_MACADDR_SET) parameter, lower device already has a macvlan port and register_netdevice() called from macvlan_common_newlink() fails (e.g. because of the invalid link name).

In this case macvlan_hash_add_source is called from macvlan_change_sources() / macvlan_common_newlink():

This adds a reference to vlan to the port's vlan_source_hash using macvlan_source_entry.

vlan is a pointer to the priv data of the link that is being created.

When register_netdevice() fails, the error is returned from macvlan_newlink() to rtnl_newlink_create():

    if (ops->newlink)
            err = ops->newlink(dev, &params, extack);
    else
            err = register_netdevice(dev);
    if (err < 0) {
            free_netdev(dev);
            goto out;
    }

and free_netdev() is called, causing a kvfree() on the struct net_device that is still referenced in the source entry attached to the lower device's macvlan port.

Now all packets sent on the macvlan port with a matching source mac address will trigger a use-after-free in macvlan_forward_source().

</quote valis>

With all that, my fix is to make sure we call macvlan_flush_sources() regardless of @create value whenever "goto destroy_macvlan_port;" path is taken.

Many thanks to valis for following up on this issue.

Database specific 
{
    "cna_assigner":  "Linux",
    "osv_generated_from":  "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/23xxx/CVE-2026-23209.json"
}
References

Affected packages

Git / git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git

Affected ranges

Type
GIT
Repo
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Events
Introduced
aa5fd0fb77486b8a6764ead8627baa14790e4280
Fixed
da5c6b8ae47e414be47e5e04def15b25d5c962dc
Fixed
5dae6b36a7cb7a4fcf4121b95e9ca7f96f816c8a
Fixed
c43d0e787cbba569ec9d11579ed370b50fab6c9c
Fixed
11ba9f0dc865136174cb98834280fb21bbc950c7
Fixed
986967a162142710076782d5b93daab93a892980
Fixed
cdedcd5aa3f3cb8b7ae0f87ab3a936d0bd583d66
Fixed
f8db6475a83649689c087a8f52486fcc53e627e9

Database specific

source 
"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-23209.json"

Linux / Kernel

Package

Name
Kernel

Affected ranges

Type
ECOSYSTEM
Events
Introduced
4.9.0
Fixed
5.10.250
Type
ECOSYSTEM
Events
Introduced
5.11.0
Fixed
5.15.200
Type
ECOSYSTEM
Events
Introduced
5.16.0
Fixed
6.1.163
Type
ECOSYSTEM
Events
Introduced
6.2.0
Fixed
6.6.124
Type
ECOSYSTEM
Events
Introduced
6.7.0
Fixed
6.12.70
Type
ECOSYSTEM
Events
Introduced
6.13.0
Fixed
6.18.10

Database specific

source 
"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-23209.json"