CyberSecBulletin
CVE-2024-26620NVD status: Modified

Linux: Out-of-bounds Write

Published Updated By the CyberSecBulletin desk

CVE-2024-26620 is a high-severity out-of-bounds write vulnerability in Linux, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions d6b8d034b576f406af920a7bee81606c027b24c6, c69d821197611678533fb3eb784fc823b921349a, cdd134d56138302976685e6c7bc4755450b3880e 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 0.63% chance of exploitation within 30 days, higher than 51% of scored CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to d6b8d034b576f406af920a7bee81606c027b24c6 or c69d821197611678533fb3eb784fc823b921349a or cdd134d56138302976685e6c7bc4755450b3880e or 850fb7fa8c684a4c6bf0e4b6978f4ddcc5d43d11, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 6.1.76 or 6.6.15 or 6.7.3, whichever matches your release line, or a later version.
  3. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux48cae940c31d2407d860d87c41d5f9871c0521db up to, but not including, d6b8d034b576f406af920a7bee81606c027b24c6; 48cae940c31d2407d860d87c41d5f9871c0521db up to, but not including, c69d821197611678533fb3eb784fc823b921349a; 48cae940c31d2407d860d87c41d5f9871c0521db up to, but not including, cdd134d56138302976685e6c7bc4755450b3880e; 48cae940c31d2407d860d87c41d5f9871c0521db up to, but not including, 850fb7fa8c684a4c6bf0e4b6978f4ddcc5d43d11; 6.0d6b8d034b576f406af920a7bee81606c027b24c6, c69d821197611678533fb3eb784fc823b921349a, cdd134d56138302976685e6c7bc4755450b3880e, 850fb7fa8c684a4c6bf0e4b6978f4ddcc5d43d11
LinuxLinux Kernel6.0 up to, but not including, 6.1.76; 6.2 up to, but not including, 6.6.15; 6.7 up to, but not including, 6.7.36.1.76, 6.6.15, 6.7.3

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
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
NoneNo data is disclosed.
Integrity
NoneNothing can be modified.
Availability
HighThe component can be taken down completely.

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

Scoring systemScoreSeverityScored by
CVSS 3.18.2HighCNA
CVSS 3.17.5HighNVD

Official description

In the Linux kernel, the following vulnerability has been resolved: s390/vfio-ap: always filter entire AP matrix The vfio_ap_mdev_filter_matrix function is called whenever a new adapter or domain is assigned to the mdev. The purpose of the function is to update the guest's AP configuration by filtering the matrix of adapters and domains assigned to the mdev. When an adapter or domain is assigned, only the APQNs associated with the APID of the new adapter or APQI of the new domain are inspected. If an APQN does not reference a queue device bound to the vfio_ap device driver, then it's APID will be filtered from the mdev's matrix when updating the guest's AP configuration. Inspecting only the APID of the new adapter or APQI of the new domain will result in passing AP queues through to a guest that are not bound to the vfio_ap device driver under certain circumstances. Consider the following: guest's AP configuration (all also assigned to the mdev's matrix): 14.0004 14.0005 14.0006 16.0004 16.0005 16.0006 unassign domain 4 unbind queue 16.0005 assign domain 4 When domain 4 is re-assigned, since only domain 4 will be inspected, the APQNs that will be examined will be: 14.0004 16.0004 Since both of those APQNs reference queue devices that are bound to the vfio_ap device driver, nothing will get filtered from the mdev's matrix when updating the guest's AP configuration. Consequently, queue 16.0005 will get passed through despite not being bound to the driver. This violates the linux device model requirement that a guest shall only be given access to devices bound to the device driver facilitating their pass-through. To resolve this problem, every adapter and domain assigned to the mdev will be inspected when filtering the mdev's matrix.

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

References

Recent Out-of-bounds Write vulnerabilities

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