CyberSecBulletin
CVE-2025-39683NVD status: Modified

Linux: Out-of-bounds Read

Published Updated By the CyberSecBulletin desk

CVE-2025-39683 is a high-severity out-of-bounds read vulnerability in Linux, with a CVSS 3.1 base score of 7.1 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions b842ef39c2ad6156c13afdec25ecc6792a9b67b9, 41b838420457802f21918df66764b6fbf829d330, 418b448e1d7470da9d4d4797f71782595ee69c49 as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.19% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to b842ef39c2ad6156c13afdec25ecc6792a9b67b9 or 41b838420457802f21918df66764b6fbf829d330 or 418b448e1d7470da9d4d4797f71782595ee69c49 or 58ff8064cb4c7eddac4da1a59da039ead586950a, whichever matches your release line, or a later version.
  2. Update SIMATIC CN 4100 to V5.0 or a later version.
  3. Update Linux Kernel to 4.5 or 4.10 or 4.15 or 4.20, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux634684d79733124f7470b226b0f42aada4426b07 up to, but not including, b842ef39c2ad6156c13afdec25ecc6792a9b67b9; 8c9af478c06bb1ab1422f90d8ecbc53defd44bc3 up to, but not including, 41b838420457802f21918df66764b6fbf829d330; 8c9af478c06bb1ab1422f90d8ecbc53defd44bc3 up to, but not including, 418b448e1d7470da9d4d4797f71782595ee69c49; 8c9af478c06bb1ab1422f90d8ecbc53defd44bc3 up to, but not including, 58ff8064cb4c7eddac4da1a59da039ead586950a; 8c9af478c06bb1ab1422f90d8ecbc53defd44bc3 up to, but not including, d0c68045b8b0f3737ed7bd6b8c83b7887014adee; 8c9af478c06bb1ab1422f90d8ecbc53defd44bc3 up to, but not including, 3079517a5ba80901fe828a06998da64b9b8749be; 8c9af478c06bb1ab1422f90d8ecbc53defd44bc3 up to, but not including, 6a909ea83f226803ea0e718f6e88613df9234d58; 24cd31752f47699b89b4b3471155c8e599a1a23a; and 15 more rangesb842ef39c2ad6156c13afdec25ecc6792a9b67b9, 41b838420457802f21918df66764b6fbf829d330, 418b448e1d7470da9d4d4797f71782595ee69c49, 58ff8064cb4c7eddac4da1a59da039ead586950a, d0c68045b8b0f3737ed7bd6b8c83b7887014adee, 3079517a5ba80901fe828a06998da64b9b8749be
SiemensSIMATIC CN 4100before V5.0V5.0
SiemensSIMATIC S7-1500 CPU 1518-4 PN/DP MFPV3.1.5 and laterNot stated
SiemensSIMATIC S7-1500 CPU 1518F-4 PN/DP MFPV3.1.5 and laterNot stated
SiemensSIPLUS S7-1500 CPU 1518-4 PN/DP MFPV3.1.5 and laterNot stated
LinuxLinux Kernel4.4.269 up to, but not including, 4.5; 4.9.269 up to, but not including, 4.10; 4.14.233 up to, but not including, 4.15; 4.19.191 up to, but not including, 4.20; 5.4.118 up to, but not including, 5.5; 5.10.36 up to, but not including, 5.10.241; 5.11.20 up to, but not including, 5.12; 5.12.3 up to, but not including, 5.15.190; and 5 more ranges4.5, 4.10, 4.15, 4.20, 5.5, 5.10.241
DebianDebian Linux11.0Not stated

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
NoneNothing can be modified.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.17.8HighCNA
CVSS 3.17.1HighNVD

Official description

In the Linux kernel, the following vulnerability has been resolved: tracing: Limit access to parser->buffer when trace_get_user failed 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.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Out-of-bounds Read

The product reads data past the end, or before the beginning, of the intended buffer.

How developers prevent this class of flaw

  • Use a language that provides appropriate memory abstractions.

More Out-of-bounds Read vulnerabilities (CWE-125)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Out-of-bounds Read vulnerabilities

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