CVE-2025-21921 Affecting kernel-debug-devel package, versions *


Severity

Recommended
low

Based on Red Hat Enterprise Linux security rating.

Do your applications use this vulnerable package?

In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.

Test your applications
  • Snyk IDSNYK-RHEL9-KERNELDEBUGDEVEL-9608553
  • published2 Apr 2025
  • disclosed1 Apr 2025

Introduced: 1 Apr 2025

NewCVE-2025-21921  (opens in a new tab)

How to fix?

There is no fixed version for RHEL:9 kernel-debug-devel.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-debug-devel package and not the kernel-debug-devel package as distributed by RHEL. See How to fix? for RHEL:9 relevant fixed versions and status.

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

net: ethtool: netlink: Allow NULL nlattrs when getting a phy_device

ethnl_req_get_phydev() is used to lookup a phy_device, in the case an ethtool netlink command targets a specific phydev within a netdev's topology.

It takes as a parameter a const struct nlattr *header that's used for error handling :

   if (!phydev) {
           NL_SET_ERR_MSG_ATTR(extack, header,
                               "no phy matching phyindex");
           return ERR_PTR(-ENODEV);
   }

In the notify path after a ->set operation however, there's no request attributes available.

The typical callsite for the above function looks like:

phydev = ethnl_req_get_phydev(req_base, tb[ETHTOOL_A_XXX_HEADER],
                  info->extack);

So, when tb is NULL (such as in the ethnl notify path), we have a nice crash.

It turns out that there's only the PLCA command that is in that case, as the other phydev-specific commands don't have a notification.

This commit fixes the crash by passing the cmd index and the nlattr array separately, allowing NULL-checking it directly inside the helper.

CVSS Base Scores

version 3.1