CyberSecBulletin
CVE-2025-39788NVD status: Modified

Linux: Out-of-bounds Write

Published Updated By the CyberSecBulletin desk

CVE-2025-39788 is a high-severity out-of-bounds write vulnerability in Linux, with a CVSS 3.1 base score of 7.8 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 01510a9e8222f11cce064410f3c2fcf0756c0a08, 098b2c8ee208c77126839047b9e6e1925bb35baa, c1f025da8f370a015e412b55cbcc583f91de8316 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 0.18% 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 01510a9e8222f11cce064410f3c2fcf0756c0a08 or 098b2c8ee208c77126839047b9e6e1925bb35baa or c1f025da8f370a015e412b55cbcc583f91de8316 or 6d53b2a134da77eb7fe65c5c7c7a3c193539a78a, 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 5.10.241 or 5.15.190 or 6.1.149 or 6.6.103, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux55f4b1f73631a0817717fe6e98517de51b4c3527 up to, but not including, 01510a9e8222f11cce064410f3c2fcf0756c0a08; 55f4b1f73631a0817717fe6e98517de51b4c3527 up to, but not including, 098b2c8ee208c77126839047b9e6e1925bb35baa; 55f4b1f73631a0817717fe6e98517de51b4c3527 up to, but not including, c1f025da8f370a015e412b55cbcc583f91de8316; 55f4b1f73631a0817717fe6e98517de51b4c3527 up to, but not including, 6d53b2a134da77eb7fe65c5c7c7a3c193539a78a; 55f4b1f73631a0817717fe6e98517de51b4c3527 up to, but not including, dc8fb963742f1a38d284946638f9358bdaa0ddee; 55f4b1f73631a0817717fe6e98517de51b4c3527 up to, but not including, 5b9f1ef293428ea9c0871d96fcec2a87c4445832; 55f4b1f73631a0817717fe6e98517de51b4c3527 up to, but not including, 01aad16c2257ab8ff33b152b972c9f2e1af47912; 5.901510a9e8222f11cce064410f3c2fcf0756c0a08, 098b2c8ee208c77126839047b9e6e1925bb35baa, c1f025da8f370a015e412b55cbcc583f91de8316, 6d53b2a134da77eb7fe65c5c7c7a3c193539a78a, dc8fb963742f1a38d284946638f9358bdaa0ddee, 5b9f1ef293428ea9c0871d96fcec2a87c4445832
SiemensSIMATIC CN 4100before V5.0V5.0
LinuxLinux Kernel5.9 up to, but not including, 5.10.241; 5.11 up to, but not including, 5.15.190; 5.16 up to, but not including, 6.1.149; 6.2 up to, but not including, 6.6.103; 6.7 up to, but not including, 6.12.44; 6.13 up to, but not including, 6.16.45.10.241, 5.15.190, 6.1.149, 6.6.103, 6.12.44, 6.16.4
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
HighData or code can be modified at will.
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:H/A:H. Scored by NVD.

Official description

In the Linux kernel, the following vulnerability has been resolved: scsi: ufs: exynos: Fix programming of HCI_UTRL_NEXUS_TYPE On Google gs101, the number of UTP transfer request slots (nutrs) is 32, and in this case the driver ends up programming the UTRL_NEXUS_TYPE incorrectly as 0. This is because the left hand side of the shift is 1, which is of type int, i.e. 31 bits wide. Shifting by more than that width results in undefined behaviour. Fix this by switching to the BIT() macro, which applies correct type casting as required. This ensures the correct value is written to UTRL_NEXUS_TYPE (0xffffffff on gs101), and it also fixes a UBSAN shift warning: UBSAN: shift-out-of-bounds in drivers/ufs/host/ufs-exynos.c:1113:21 shift exponent 32 is too large for 32-bit type 'int' For consistency, apply the same change to the nutmrs / UTMRL_NEXUS_TYPE write.

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

The underlying weakness: Out-of-bounds Write

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

How developers prevent this class of flaw

  • Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer. Be wary that a language's interface to native code may still be subject to overflows, even if the language itself is theoretically safe.
  • Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Examples include the Safe C String Library (SafeStr) by Messier and Viega, and the Strsafe.h library from Microsoft. These libraries provide safer versions of overflow-prone string-handling functions.
  • Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.

More Out-of-bounds Write vulnerabilities (CWE-787)

Timeline

  1. CVE record published.
  2. Record last changed materially (score, affected products, status or references).

References

Recent Out-of-bounds Write vulnerabilities

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