CVE-2025-21777 Affecting kernel-uek-modules-extra-netfilter package, versions <0:6.12.0-101.33.4.3.el9uek


Severity

Recommended
high

Based on Oracle Linux security rating.

Threat Intelligence

EPSS
0.04% (11th percentile)

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  • Snyk IDSNYK-ORACLE9-KERNELUEKMODULESEXTRANETFILTER-10790729
  • published19 Jul 2025
  • disclosed27 Feb 2025

Introduced: 27 Feb 2025

CVE-2025-21777  (opens in a new tab)

How to fix?

Upgrade Oracle:9 kernel-uek-modules-extra-netfilter to version 0:6.12.0-101.33.4.3.el9uek or higher.
This issue was patched in ELSA-2025-20480.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-uek-modules-extra-netfilter package and not the kernel-uek-modules-extra-netfilter package as distributed by Oracle. See How to fix? for Oracle:9 relevant fixed versions and status.

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

ring-buffer: Validate the persistent meta data subbuf array

The meta data for a mapped ring buffer contains an array of indexes of all the subbuffers. The first entry is the reader page, and the rest of the entries lay out the order of the subbuffers in how the ring buffer link list is to be created.

The validator currently makes sure that all the entries are within the range of 0 and nr_subbufs. But it does not check if there are any duplicates.

While working on the ring buffer, I corrupted this array, where I added duplicates. The validator did not catch it and created the ring buffer link list on top of it. Luckily, the corruption was only that the reader page was also in the writer path and only presented corrupted data but did not crash the kernel. But if there were duplicates in the writer side, then it could corrupt the ring buffer link list and cause a crash.

Create a bitmask array with the size of the number of subbuffers. Then clear it. When walking through the subbuf array checking to see if the entries are within the range, test if its bit is already set in the subbuf_mask. If it is, then there is duplicates and fail the validation. If not, set the corresponding bit and continue.

CVSS Base Scores

version 3.1