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-15569574
  • published15 Mar 2026
  • disclosed13 Feb 2026

Introduced: 13 Feb 2026

CVE-2026-23111  (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:

netfilter: nf_tables: fix inverted genmask check in nft_map_catchall_activate()

nft_map_catchall_activate() has an inverted element activity check compared to its non-catchall counterpart nft_mapelem_activate() and compared to what is logically required.

nft_map_catchall_activate() is called from the abort path to re-activate catchall map elements that were deactivated during a failed transaction. It should skip elements that are already active (they don't need re-activation) and process elements that are inactive (they need to be restored). Instead, the current code does the opposite: it skips inactive elements and processes active ones.

Compare the non-catchall activate callback, which is correct:

nft_mapelem_activate(): if (nft_set_elem_active(ext, iter->genmask)) return 0; /* skip active, process inactive */

With the buggy catchall version:

nft_map_catchall_activate(): if (!nft_set_elem_active(ext, genmask)) continue; /* skip inactive, process active */

The consequence is that when a DELSET operation is aborted, nft_setelem_data_activate() is never called for the catchall element. For NFT_GOTO verdict elements, this means nft_data_hold() is never called to restore the chain->use reference count. Each abort cycle permanently decrements chain->use. Once chain->use reaches zero, DELCHAIN succeeds and frees the chain while catchall verdict elements still reference it, resulting in a use-after-free.

This is exploitable for local privilege escalation from an unprivileged user via user namespaces + nftables on distributions that enable CONFIG_USER_NS and CONFIG_NF_TABLES.

Fix by removing the negation so the check matches nft_mapelem_activate(): skip active elements, process inactive ones.

CVSS Base Scores

version 3.1