CVE-2025-38457 Affecting kernel-uek64k-core package, versions <0:6.12.0-103.40.4.1.el10uek


Severity

Recommended
high

Based on Oracle Linux security rating.

Threat Intelligence

EPSS
0.04% (9th percentile)

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  • Snyk IDSNYK-ORACLE10-KERNELUEK64KCORE-12572157
  • published10 Sept 2025
  • disclosed25 Jul 2025

Introduced: 25 Jul 2025

CVE-2025-38457  (opens in a new tab)

How to fix?

Upgrade Oracle:10 kernel-uek64k-core to version 0:6.12.0-103.40.4.1.el10uek or higher.
This issue was patched in ELSA-2025-20551.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-uek64k-core package and not the kernel-uek64k-core package as distributed by Oracle. See How to fix? for Oracle:10 relevant fixed versions and status.

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

net/sched: Abort __tc_modify_qdisc if parent class does not exist

Lion's patch [1] revealed an ancient bug in the qdisc API. Whenever a user creates/modifies a qdisc specifying as a parent another qdisc, the qdisc API will, during grafting, detect that the user is not trying to attach to a class and reject. However grafting is performed after qdisc_create (and thus the qdiscs' init callback) is executed. In qdiscs that eventually call qdisc_tree_reduce_backlog during init or change (such as fq, hhf, choke, etc), an issue arises. For example, executing the following commands:

sudo tc qdisc add dev lo root handle a: htb default 2 sudo tc qdisc add dev lo parent a: handle beef fq

Qdiscs such as fq, hhf, choke, etc unconditionally invoke qdisc_tree_reduce_backlog() in their control path init() or change() which then causes a failure to find the child class; however, that does not stop the unconditional invocation of the assumed child qdisc's qlen_notify with a null class. All these qdiscs make the assumption that class is non-null.

The solution is ensure that qdisc_leaf() which looks up the parent class, and is invoked prior to qdisc_create(), should return failure on not finding the class. In this patch, we leverage qdisc_leaf to return ERR_PTRs whenever the parentid doesn't correspond to a class, so that we can detect it earlier on and abort before qdisc_create is called.

[1] https://lore.kernel.org/netdev/d912cbd7-193b-4269-9857-525bee8bbb6a@gmail.com/

CVSS Base Scores

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