high 7.8

CVE-2025-39683 json

tracing: Limit access to parser->buffer when trace_get_user failed

published 2025-09-05 14 mo ago modified 2026-10-19 20 d ago also EUVD-2025-31541

cvss: 7.8; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 8%
public exploits: 0; none known

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

When the length of the string written to set_ftrace_filter exceeds FTRACE_BUFF_MAX, the following KASAN alarm will be triggered:

BUG: KASAN: slab-out-of-bounds in strsep+0x18c/0x1b0 Read of size 1 at addr ffff0000d00bd5ba by task ash/165

CPU: 1 UID: 0 PID: 165 Comm: ash Not tainted 6.16.0-g6bcdbd62bd56-dirty Hardware name: linux,dummy-virt (DT) Call trace: show_stack+0x34/0x50 (C) dump_stack_lvl+0xa0/0x158 print_address_description.constprop.0+0x88/0x398 print_report+0xb0/0x280 kasan_report+0xa4/0xf0 __asan_report_load1_noabort+0x20/0x30 strsep+0x18c/0x1b0 ftrace_process_regex.isra.0+0x100/0x2d8 ftrace_regex_release+0x484/0x618 __fput+0x364/0xa58 ____fput+0x28/0x40 task_work_run+0x154/0x278 do_notify_resume+0x1f0/0x220 el0_svc+0xec/0xf0 el0t_64_sync_handler+0xa0/0xe8 el0t_64_sync+0x1ac/0x1b0

The reason is that trace_get_user will fail when processing a string longer than FTRACE_BUFF_MAX, but not set the end of parser->buffer to 0. Then an OOB access will be triggered in ftrace_regex_release-> ftrace_process_regex->strsep->strpbrk. We can solve this problem by limiting access to parser->buffer when trace_get_user failed.

Patch / fix

fixed in 2 distros 5 links 7

Linux Linux 4.5, 4.10, 4.15, 4.20, 5.5, 5.10.241, 5.12, 5.13, 5.15.190, 6.1.149, 6.6.103, 6.12.44, 6.16.4, 6.17
Siemens SIMATIC CN 4100 V5.0

debian ubuntu suse opensuse azure linux

linux Debian 12 6.1.153-1
linux Debian 13 6.12.48-1
linux Debian 14 6.16.5-1

debian advisories DEBIAN-CVE-2025-39683

linux Ubuntu 22.04 LTS 5.15.0-163.173
linux Ubuntu 24.04 LTS 6.8.0-100.100
linux-aws Ubuntu 22.04 LTS 5.15.0-1097.104
linux-aws Ubuntu 24.04 LTS 6.8.0-1046.49
linux-gcp Ubuntu 22.04 LTS 5.15.0-1097.106
linux-gcp Ubuntu 24.04 LTS 6.8.0-1047.50
linux-gke Ubuntu 22.04 LTS 5.15.0-1093.99
linux-gke Ubuntu 24.04 LTS 6.8.0-1043.48

ubuntu advisories UBUNTU-CVE-2025-39683

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

kernel-rt Real Time Module 15 SP6, openSUSE Leap 15.6 6.4.0-150600.10.58.1
kernel-syms-rt Real Time Module 15 SP6, openSUSE Leap 15.6 6.4.0-150600.10.58.1
kernel-rt_debug Real Time Module 15 SP6, openSUSE Leap 15.6 6.4.0-150600.10.58.1
kernel-source-rt Real Time Module 15 SP6, openSUSE Leap 15.6 6.4.0-150600.10.58.1
kernel-rt Linux Micro 6.1, Linux Micro 6.0 6.4.0-38.1
kernel-source-rt Linux Micro 6.1, Linux Micro 6.0 6.4.0-38.1
kernel-rt Linux Micro 6.2 6.12.0-160000.6.1
kernel-64kb SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 6.12.0-160000.6.1

suse advisories SUSE-SU-2025:4301-1 SUSE-SU-2025:21052-1 SUSE-SU-2025:21064-1 SUSE-SU-2025:21074-1 SUSE-SU-2025:21139-1 SUSE-SU-2026:20560-1

kernel-rt openSUSE Leap 16.0 6.12.0-160000.6.1
dtb-aarch64 openSUSE Leap 16.0 6.12.0-160000.6.1
kernel-64kb openSUSE Leap 16.0 6.12.0-160000.6.1
kernel-syms openSUSE Leap 16.0 6.12.0-160000.6.1
kernel-obs-qa openSUSE Leap 16.0 6.12.0-160000.6.1
kernel-source openSUSE Leap 16.0 6.12.0-160000.6.1
kernel-default openSUSE Leap 16.0 6.12.0-160000.6.1
kernel-kvmsmall openSUSE Leap 16.0 6.12.0-160000.6.1

opensuse advisories openSUSE-SU-2025:20081-1

kernel Azure Linux 3.0 6.6.104.2-1
kernel CBL-Mariner 2.0 5.15.200.1-1

azure linux advisories AZL-67037 AZL-73695

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-39683 updated 2026-11-05 cvss 4.4

kernel: tracing: Limit access to parser->buffer when trace_get_user failed

Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernel
affected: no fix available “Fix deferred”
Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more
not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

cisa ICSA-25-162-05 updated 2026-05-14 cvss 7.1

Siemens SIMATIC S7-1500 CPU family

Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) >= 3.1.5 Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) >= 3.1.5 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) >= 3.1.5 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) >= 3.1.5 Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) >= 3.1.5
affected: mitigation, no fix available

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

cisa ICSA-26-134-10 updated 2026-05-14 cvss 7.1

Siemens SIMATIC

Siemens SIMATIC CN 4100 < 5.0
affected: fixed in V5.0 support.industry.siemens.com

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: total
Assessed: 24 d ago (2026-10-15)

Exploit prediction

0.19% chance of exploitation in the next 30 days, higher than 8% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	7.8	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD	3.1	7.1	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

Affected products

Linux Linux
Siemens SIMATIC CN 4100
Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP
Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP
Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP

Classification

Weakness

CWE-125 Out-of-bounds Read

Technology feeds

Linux kernel rss critical rss

References

Sources

CVE List CVE-2025-39683
NVD CVE-2025-39683

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary