Use After Free Affecting kernel-uek-doc package, versions <0:5.15.0-318.199.3.2.el8uek


Severity

Recommended
0.0
high
0
10

Based on Oracle Linux security rating.

Threat Intelligence

EPSS
0.04% (10th percentile)

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  • Snyk IDSNYK-ORACLE8-KERNELUEKDOC-15601407
  • published15 Mar 2026
  • disclosed14 Feb 2026

Introduced: 14 Feb 2026

CVE-2026-23209  (opens in a new tab)
CWE-416  (opens in a new tab)

How to fix?

Upgrade Oracle:8 kernel-uek-doc to version 0:5.15.0-318.199.3.2.el8uek or higher.
This issue was patched in ELSA-2026-50145.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-uek-doc package and not the kernel-uek-doc package as distributed by Oracle. See How to fix? for Oracle:8 relevant fixed versions and status.

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:

<quote valis>

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-&gt;newlink)
            err = ops-&gt;newlink(dev, &amp;params, extack);
    else
            err = register_netdevice(dev);
    if (err &lt; 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.

CVSS Base Scores

version 3.1