CyberSecBulletin
CVE-2025-38685NVD status: Modified

Linux: Out-of-bounds Write

Published Updated By the CyberSecBulletin desk

CVE-2025-38685 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 078e62bffca4b7e72e8f3550eb063ab981c36c7a, 4c4d7ddaf1d43780b106bedc692679f965dc5a3a, 27b118aebdd84161c8ff5ce49d9d536f2af10754 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 078e62bffca4b7e72e8f3550eb063ab981c36c7a or 4c4d7ddaf1d43780b106bedc692679f965dc5a3a or 27b118aebdd84161c8ff5ce49d9d536f2af10754 or ed9b8e5016230868c8d813d9179523f729fec8c6, 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 5.15.190 or 6.1.149 or 6.6.103 or 6.12.43, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 078e62bffca4b7e72e8f3550eb063ab981c36c7a; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 4c4d7ddaf1d43780b106bedc692679f965dc5a3a; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 27b118aebdd84161c8ff5ce49d9d536f2af10754; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, ed9b8e5016230868c8d813d9179523f729fec8c6; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 56701bf9eeb63219e378cb7fcbd066ea4eaeeb50; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, cfec17721265e72e50cc69c6004fe3475cd38df2; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, af0db3c1f898144846d4c172531a199bb3ca375d; 2.6.12078e62bffca4b7e72e8f3550eb063ab981c36c7a, 4c4d7ddaf1d43780b106bedc692679f965dc5a3a, 27b118aebdd84161c8ff5ce49d9d536f2af10754, ed9b8e5016230868c8d813d9179523f729fec8c6, 56701bf9eeb63219e378cb7fcbd066ea4eaeeb50, cfec17721265e72e50cc69c6004fe3475cd38df2
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 Kernel2.6.13 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, 6.12.43; 6.13 up to, but not including, 6.15.11; 6.16 up to, but not including, 6.16.2; 2.6.125.15.190, 6.1.149, 6.6.103, 6.12.43, 6.15.11, 6.16.2
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.

Scoring systemScoreSeverityScored by
CVSS 3.17.8HighCNA
CVSS 3.17.8HighNVD

Official description

In the Linux kernel, the following vulnerability has been resolved: fbdev: Fix vmalloc out-of-bounds write in fast_imageblit This issue triggers when a userspace program does an ioctl FBIOPUT_CON2FBMAP by passing console number and frame buffer number. Ideally this maps console to frame buffer and updates the screen if console is visible. As part of mapping it has to do resize of console according to frame buffer info. if this resize fails and returns from vc_do_resize() and continues further. At this point console and new frame buffer are mapped and sets display vars. Despite failure still it continue to proceed updating the screen at later stages where vc_data is related to previous frame buffer and frame buffer info and display vars are mapped to new frame buffer and eventully leading to out-of-bounds write in fast_imageblit(). This bheviour is excepted only when fg_console is equal to requested console which is a visible console and updates screen with invalid struct references in fbcon_putcs().

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

Third-party and government advisories

Recent Out-of-bounds Write vulnerabilities

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