NVD / CVE Program· CNA Linux

CVE-2025-38350: net/sched: Always pass notifications when child class becomes empty

HighCVSS 7.8 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 31/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 0.29% (FIRST EPSS).
Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
Fixed version: Linux Linux 103406b38c600fec1fe375a77b27d87e314aea09, 3b290923ad2b23596208c1e29520badef4356a43, 5.10.240; cbl2 kernel 5.15.186.1-1 on CBL Mariner 2.0 5.15.200.1-1.

Low priority for now. Upgrade to Linux Linux 103406b38c600fec1fe375a77b27d87e314aea09, 3b290923ad2b23596208c1e29520badef4356a43, 5.10.240; cbl2 kernel 5.15.186.1-1 on CBL Mariner 2.0 5.15.200.1-1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

In the Linux kernel, the following vulnerability has been resolved: net/sched: Always pass notifications when child class becomes empty Certain classful qdiscs may invoke their classes' dequeue handler on an enqueue operation. This may unexpectedly empty the child qdisc and thus make an in-flight class passive via qlen_notify(). Most qdiscs do not expect such behaviour at this point in time and may re-activate the class eventually anyways which will lead to a use-after-free. The referenced fix commit attempted to fix this behavior for the HFSC case by moving the backlog accounting around, though this turned out to be incomplete since the parent's parent may run into the issue too. The following reproducer demonstrates this use-after-free: tc qdisc add dev lo root handle 1: drr tc filter add dev lo parent 1: basic classid 1:1 tc class add dev lo parent 1: classid 1:1 drr tc qdisc add dev lo parent 1:1 handle 2: hfsc def 1 tc class add dev lo parent 2: classid 2:1 hfsc rt m1 8 d 1 m2 0 tc qdisc add dev lo parent 2:1 handle 3: netem tc qdisc add dev lo parent 3:1 handle 4: blackhole echo 1 | socat -u STDIN UDP4-DATAGRAM:127.0.0.1:8888 tc class delete dev lo classid 1:1 echo 1 | socat -u STDIN UDP4-DATAGRAM:127.0.0.1:8888 Since backlog accounting issues leading to a use-after-frees on stale class pointers is a recurring pattern at this point, this patch takes a different approach. Instead of trying to fix the accounting, the patch ensures that qdisc_tree_reduce_backlog always calls qlen_notify when the child qdisc is empty. This solves the problem because deletion of qdiscs always involves a call to qdisc_reset() and / or qdisc_purge_queue() which ultimately resets its qlen to 0 thus causing the following qdisc_tree_reduce_backlog() to report to the parent. Note that this may call qlen_notify on passive classes multiple times. This is not a problem after the recent patch series that made all the classful qdiscs qlen_notify() handlers idempotent.

Memory safety

Published: Jul 19, 2025
Updated: Oct 15, 2026
EPSS: 0.2% · 22th percentile
CWE: CWE-416

Report tools

JSON

Action score

Monitor

Low priority for now.

CVSS: 31 / 40 · 7.8 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.2%

CISA SSVC decision

Exploitation: none
Automatable: no
Technical impact: total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD: 7.8
CNA · Linux: 7.8; agree

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

Not in KEV: no record of exploitation in the wild
No public exploit code on record
A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Is your version affected? Check it

Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

Vendor	Product	CPE
linux	linux kernel	cpe:2.3:o:linux:linux_kernel
debian	debian linux	cpe:2.3:o:debian:debian_linux

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

Linux Linux
- 3f3a22eebbc32b4fa8ce9c1d5f9db214b45b9335, 6.15affected
- 1034e3310752e8675e313f7271b348914008719a and later · before 3b290923ad2b23596208c1e29520badef4356a43affected · git
- f9f593e34d2fb67644372c8f7b033bdc622ad228 and later · before e9921b57dca05ac5f4fa1fa8e993d4f0ee52e2b7affected · git
- 89c301e929a0db14ebd94b4d97764ce1d6981653 and later · before e269f29e9395527bc00c213c6b15da04ebb35070affected · git
- f1dde3eb17dc1b8bd07aed00004b1e05fc87a3d4 and later · before 7874c9c132e906a52a187d045995b115973c93fbaffected · git
- 93c276942e75de0e5bc91576300d292e968f5a02 and later · before f680a4643c6f71e758d8fe0431a958e9a6a4f59daffected · git
- 49b21795b8e5654a7df3d910a12e1060da4c04cf and later · before a553afd91f55ff39b1e8a1c4989a29394c9e0472affected · git
- 3f981138109f63232a5fb7165938d4c945cc1b9d and later · before a44acdd9e84a211989ff4b9b92bf3545d8456ad5affected · git
- 3f981138109f63232a5fb7165938d4c945cc1b9d and later · before 103406b38c600fec1fe375a77b27d87e314aea09affected · git
- 5.4.294 and later · before 5.4.296affected · semver

Affected versions · NVD (11)

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

debian debian linux11.0
linux linux kernel5.10.238 and later · before 5.10.240
linux linux kernel5.15.185 and later · before 5.15.187
linux linux kernel6.1.141 and later · before 6.1.144
linux linux kernel6.6.93 and later · before 6.6.97
linux linux kernel5.4.294 and later · before 5.4.296
linux linux kernel6.14.9 and later · before 6.15
linux linux kernel6.15.1 and later · before 6.15.6
linux linux kernel6.12.31 and later · before 6.12.37
linux linux kernel6.15
linux linux kernel6.16

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Ecosystem	Package	Affected range	Fix
AlmaLinux:10	kernel-abi-stablelists	before 6.12.0-55.31.1.el10_0	6.12.0-55.31.1.el10_0
AlmaLinux:10	kernel-doc	before 6.12.0-55.31.1.el10_0	6.12.0-55.31.1.el10_0
AlmaLinux:8	bpftool	before 4.18.0-553.75.1.el8_10	4.18.0-553.75.1.el8_10
AlmaLinux:8	kernel	before 4.18.0-553.75.1.el8_10	4.18.0-553.75.1.el8_10
AlmaLinux:8	kernel-abi-stablelists	before 4.18.0-553.75.1.el8_10	4.18.0-553.75.1.el8_10
AlmaLinux:8	kernel-core	before 4.18.0-553.75.1.el8_10	4.18.0-553.75.1.el8_10
AlmaLinux:8	kernel-cross-headers	before 4.18.0-553.75.1.el8_10	4.18.0-553.75.1.el8_10
AlmaLinux:8	kernel-debug	before 4.18.0-553.75.1.el8_10	4.18.0-553.75.1.el8_10
AlmaLinux:8	kernel-debug-core	before 4.18.0-553.75.1.el8_10	4.18.0-553.75.1.el8_10
AlmaLinux:8	kernel-debug-devel	before 4.18.0-553.75.1.el8_10	4.18.0-553.75.1.el8_10
AlmaLinux:8	kernel-debug-modules	before 4.18.0-553.75.1.el8_10	4.18.0-553.75.1.el8_10
AlmaLinux:8	kernel-debug-modules-extra	before 4.18.0-553.75.1.el8_10	4.18.0-553.75.1.el8_10
AlmaLinux:8	kernel-devel	before 4.18.0-553.75.1.el8_10	4.18.0-553.75.1.el8_10
AlmaLinux:8	kernel-doc	before 4.18.0-553.75.1.el8_10	4.18.0-553.75.1.el8_10
AlmaLinux:8	kernel-headers	before 4.18.0-553.75.1.el8_10	4.18.0-553.75.1.el8_10
AlmaLinux:8	kernel-modules	before 4.18.0-553.75.1.el8_10	4.18.0-553.75.1.el8_10
AlmaLinux:8	kernel-modules-extra	before 4.18.0-553.75.1.el8_10	4.18.0-553.75.1.el8_10
AlmaLinux:8	kernel-rt	before 4.18.0-553.75.1.rt7.416.el8_10	4.18.0-553.75.1.rt7.416.el8_10
AlmaLinux:8	kernel-rt-core	before 4.18.0-553.75.1.rt7.416.el8_10	4.18.0-553.75.1.rt7.416.el8_10
AlmaLinux:8	kernel-rt-debug	before 4.18.0-553.75.1.rt7.416.el8_10	4.18.0-553.75.1.rt7.416.el8_10
AlmaLinux:8	kernel-rt-debug-core	before 4.18.0-553.75.1.rt7.416.el8_10	4.18.0-553.75.1.rt7.416.el8_10
AlmaLinux:8	kernel-rt-debug-devel	before 4.18.0-553.75.1.rt7.416.el8_10	4.18.0-553.75.1.rt7.416.el8_10
AlmaLinux:8	kernel-rt-debug-modules	before 4.18.0-553.75.1.rt7.416.el8_10	4.18.0-553.75.1.rt7.416.el8_10
AlmaLinux:8	kernel-rt-debug-modules-extra	before 4.18.0-553.75.1.rt7.416.el8_10	4.18.0-553.75.1.rt7.416.el8_10

+96

Same product

linux: all records

Other highest-scoring records for the same primary product.

CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
90Now
CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe…KEV
89Now
CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
85Now

Published before and after this one in the same product

← EarlierCVE-2025-38346Jul 10, 2025 · ftrace: Fix UAF when lookup kallsym after ftrace disabled
31Monitor
← EarlierCVE-2025-38349Jul 18, 2025 · eventpoll: don't decrement ep refcount while still holding the ep mutex
31Monitor
Later →CVE-2025-38351Jul 19, 2025 · KVM: x86/hyper-v: Skip non-canonical addresses during PV TLB flush
22Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / package	Fixed version	Source
Linux Linux	103406b38c600fec1fe375a77b27d87e314aea09	Vendor (CNA)
Linux Linux	3b290923ad2b23596208c1e29520badef4356a43	Vendor (CNA)
Linux Linux	5.10.240	Vendor (CNA)
Linux Linux	5.15.187	Vendor (CNA)
Linux Linux	5.4.296	Vendor (CNA)
Linux Linux	6.1.144	Vendor (CNA)
Linux Linux	6.12.37	Vendor (CNA)
Linux Linux	6.15	Vendor (CNA)
Linux Linux	6.6.97	Vendor (CNA)
Linux Linux	7874c9c132e906a52a187d045995b115973c93fb	Vendor (CNA)
Linux Linux	a44acdd9e84a211989ff4b9b92bf3545d8456ad5	Vendor (CNA)
Linux Linux	a553afd91f55ff39b1e8a1c4989a29394c9e0472	Vendor (CNA)
Linux Linux	e269f29e9395527bc00c213c6b15da04ebb35070	Vendor (CNA)
Linux Linux	e9921b57dca05ac5f4fa1fa8e993d4f0ee52e2b7	Vendor (CNA)
Linux Linux	f680a4643c6f71e758d8fe0431a958e9a6a4f59d	Vendor (CNA)
cbl2 kernel 5.15.186.1-1 on CBL Mariner 2.0	5.15.200.1-1 · CBL-Mariner Releases	Microsoft (MSRC)
almalinux:kernel	5.14.0-570.39.1.el9_6 · AlmaLinux:9	Package registry (OSV)
almalinux:kernel-64k	5.14.0-570.39.1.el9_6 · AlmaLinux:9	Package registry (OSV)
almalinux:kernel-64k-core	5.14.0-570.39.1.el9_6 · AlmaLinux:9	Package registry (OSV)
almalinux:kernel-64k-debug	5.14.0-570.39.1.el9_6 · AlmaLinux:9	Package registry (OSV)
almalinux:kernel-64k-debug-core	5.14.0-570.39.1.el9_6 · AlmaLinux:9	Package registry (OSV)
almalinux:kernel-64k-debug-devel	5.14.0-570.39.1.el9_6 · AlmaLinux:9	Package registry (OSV)
almalinux:kernel-64k-debug-devel-matched	5.14.0-570.39.1.el9_6 · AlmaLinux:9	Package registry (OSV)
almalinux:kernel-64k-debug-modules	5.14.0-570.39.1.el9_6 · AlmaLinux:9	Package registry (OSV)
almalinux:kernel-64k-debug-modules-core	5.14.0-570.39.1.el9_6 · AlmaLinux:9	Package registry (OSV)
almalinux:kernel-64k-debug-modules-extra	5.14.0-570.39.1.el9_6 · AlmaLinux:9	Package registry (OSV)
almalinux:kernel-64k-devel	5.14.0-570.39.1.el9_6 · AlmaLinux:9	Package registry (OSV)
almalinux:kernel-64k-devel-matched	5.14.0-570.39.1.el9_6 · AlmaLinux:9	Package registry (OSV)
debian:linux	6.1.147-1 · Debian:12	Package registry (OSV)
red hat:bpftool	0:3.10.0-1062.99.1.el7 · Red Hat:rhel_aus:7.7::server	Package registry (OSV)

+24

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · variant or chain candidate · public bounty program.

Technical details

Attack conditions

Someone with local access to the system can trigger it.
A low-privileged account is enough.
No user action is required.
No special conditions are required; it is repeatable.

If successful

Confidentiality: high · data can be read
Integrity: high · data or configuration can be modified
Availability: high · the service can be disrupted

Attack vector: Local
Attack complexity: Low
Privileges required: Low
User interaction: None
Scope: Unchanged
Confidentiality impact: High
Integrity impact: High
Availability impact: High

Weakness class (CWE)

CWE-416 · Use After Free

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

nvd-primary

Root cause

After a memory region is freed, another reference pointing to it is still used. By then, the same region may have been allocated for different data.

The bug in code

The whole CWE-416 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1free(dev->buf);
2/* ... another thread is still running ... */
3process(dev->buf);

Fixed

1lock(&dev->lock);
2free(dev->buf);
3dev->buf = NULL;
4unlock(&dev->lock);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log (1)

Fix✗ → ✓Sep 28, 2026, 10:08 PM UTC

For records you follow, these changes also arrive as notifications. →

References

git.kernel.org/stable/c/103406b38c600fec1fe375a77b27d87e314aea09

Show all references (11 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records