CyberSecBulletin
CVE-2026-68287NVD status: Received

Linux: Incorrect Calculation of Buffer Size

Published Updated By the CyberSecBulletin desk

CVE-2026-68287 is a high-severity incorrect calculation of buffer size 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 1275a4769c126405c6c63b6372daff120ac679a6, 0da8f531336b28a59b23e5a67d40eaed15906201, 6048ed2dfb33426c8aef32f8d225ea91c66813db 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 0.68% chance of exploitation within 30 days, higher than 53% of scored CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to 1275a4769c126405c6c63b6372daff120ac679a6 or 0da8f531336b28a59b23e5a67d40eaed15906201 or 6048ed2dfb33426c8aef32f8d225ea91c66813db or 925669d4cfd47a9019ab29b40676215bab5dae35, whichever matches your release line, or a later version.
  2. 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
LinuxLinuxca30707dee2bc8bc81cfd8b4277fe90f7ca6df1f up to, but not including, 1275a4769c126405c6c63b6372daff120ac679a6; ca30707dee2bc8bc81cfd8b4277fe90f7ca6df1f up to, but not including, 0da8f531336b28a59b23e5a67d40eaed15906201; ca30707dee2bc8bc81cfd8b4277fe90f7ca6df1f up to, but not including, 6048ed2dfb33426c8aef32f8d225ea91c66813db; ca30707dee2bc8bc81cfd8b4277fe90f7ca6df1f up to, but not including, 925669d4cfd47a9019ab29b40676215bab5dae35; ca30707dee2bc8bc81cfd8b4277fe90f7ca6df1f up to, but not including, 4a9e30764e80693bcf875c776170edce20f94fe0; ca30707dee2bc8bc81cfd8b4277fe90f7ca6df1f up to, but not including, 7089f7ab99c89f443c92d8fcc585e63f2727f0b3; 5.41275a4769c126405c6c63b6372daff120ac679a6, 0da8f531336b28a59b23e5a67d40eaed15906201, 6048ed2dfb33426c8aef32f8d225ea91c66813db, 925669d4cfd47a9019ab29b40676215bab5dae35, 4a9e30764e80693bcf875c776170edce20f94fe0, 7089f7ab99c89f443c92d8fcc585e63f2727f0b3

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 CNA.

Official description

In the Linux kernel, the following vulnerability has been resolved: drop_monitor: fix size calculations for 64-bit attributes net_dm_packet_report_fill() and net_dm_hw_packet_report_fill() use nla_put_u64_64bit() to append 64-bit attributes (NET_DM_ATTR_PC and NET_DM_ATTR_TIMESTAMP). On 32-bit architectures without CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS, nla_put_u64_64bit() may append a 4-byte NET_DM_ATTR_PAD attribute for 64-bit alignment. However, net_dm_packet_report_size() and net_dm_hw_packet_report_size() used nla_total_size(sizeof(u64)) instead of nla_total_size_64bit(sizeof(u64)), budgeting 12 bytes instead of up to 16 bytes. This under-estimation of SKB size can lead to an skb_over_panic() when __nla_reserve() or skb_put() is subsequently called. Fix this by using nla_total_size_64bit(sizeof(u64)) in both size calculations.

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

The underlying weakness: Incorrect Calculation of Buffer Size

The product does not correctly calculate the size to be used when allocating a buffer.

How developers prevent this class of flaw

  • When allocating a buffer for the purpose of transforming, converting, or encoding an input, allocate enough memory to handle the largest possible encoding. For example, in a routine that converts & characters to & for HTML entity encoding, the output buffer needs to be at least 5 times as large as the input buffer.
  • Understand the programming language's underlying representation and how it interacts with numeric calculation (CWE-681). Pay close attention to byte size discrepancies, precision, signed/unsigned distinctions, truncation, conversion and casting between types, not-a-number calculations, and how the language handles numbers that are too large or too small for its underlying representation. Also be careful to account for 32-bit, 64-bit, and other potential differences that may affect the numeric representation.
  • Perform input validation on any numeric input by ensuring that it is within the expected range. Enforce that the input meets both the minimum and maximum requirements for the expected range.

More Incorrect Calculation of Buffer Size vulnerabilities (CWE-131)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Incorrect Calculation of Buffer Size vulnerabilities

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