CVE-2026-23074 Affecting perf package, versions <0:4.18.0-553.107.1.el8_10


Severity

Recommended
high

Based on Oracle Linux security rating.

Threat Intelligence

EPSS
0.04% (14th percentile)

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  • Snyk IDSNYK-ORACLE8-PERF-15351786
  • published25 Feb 2026
  • disclosed4 Feb 2026

Introduced: 4 Feb 2026

CVE-2026-23074  (opens in a new tab)

How to fix?

Upgrade Oracle:8 perf to version 0:4.18.0-553.107.1.el8_10 or higher.
This issue was patched in ELSA-2026-3083.

NVD Description

Note: Versions mentioned in the description apply only to the upstream perf package and not the perf 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:

net/sched: Enforce that teql can only be used as root qdisc

Design intent of teql is that it is only supposed to be used as root qdisc. We need to check for that constraint.

Although not important, I will describe the scenario that unearthed this issue for the curious.

GangMin Kim <km.kim1503@gmail.com> managed to concot a scenario as follows:

ROOT qdisc 1:0 (QFQ) ├── class 1:1 (weight=15, lmax=16384) netem with delay 6.4s └── class 1:2 (weight=1, lmax=1514) teql

GangMin sends a packet which is enqueued to 1:1 (netem). Any invocation of dequeue by QFQ from this class will not return a packet until after 6.4s. In the meantime, a second packet is sent and it lands on 1:2. teql's enqueue will return success and this will activate class 1:2. Main issue is that teql only updates the parent visible qlen (sch->q.qlen) at dequeue. Since QFQ will only call dequeue if peek succeeds (and teql's peek always returns NULL), dequeue will never be called and thus the qlen will remain as 0. With that in mind, when GangMin updates 1:2's lmax value, the qfq_change_class calls qfq_deact_rm_from_agg. Since the child qdisc's qlen was not incremented, qfq fails to deactivate the class, but still frees its pointers from the aggregate. So when the first packet is rescheduled after 6.4 seconds (netem's delay), a dangling pointer is accessed causing GangMin's causing a UAF.

CVSS Base Scores

version 3.1