CyberSecBulletin
CVE-2024-39480NVD status: Modified

Linux: Buffer Copy without Checking Size of Input

Published Updated By the CyberSecBulletin desk

CVE-2024-39480 is a high-severity buffer copy without checking size of input 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 fb824a99e148ff272a53d71d84122728b5f00992, ddd2972d8e2dee3b33e8121669d55def59f0be8a, cfdc2fa4db57503bc6d3817240547c8ddc55fa96 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 0.27% 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 fb824a99e148ff272a53d71d84122728b5f00992 or ddd2972d8e2dee3b33e8121669d55def59f0be8a or cfdc2fa4db57503bc6d3817240547c8ddc55fa96 or f636a40834d22e5e3fc748f060211879c056cd33, whichever matches your release line, or a later version.
  2. Update linux_kernel to fb824a99e148 or ddd2972d8e2d or cfdc2fa4db57 or f636a40834d2, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux5d5314d6795f3c1c0f415348ff8c51f7de042b77 up to, but not including, fb824a99e148ff272a53d71d84122728b5f00992; 5d5314d6795f3c1c0f415348ff8c51f7de042b77 up to, but not including, ddd2972d8e2dee3b33e8121669d55def59f0be8a; 5d5314d6795f3c1c0f415348ff8c51f7de042b77 up to, but not including, cfdc2fa4db57503bc6d3817240547c8ddc55fa96; 5d5314d6795f3c1c0f415348ff8c51f7de042b77 up to, but not including, f636a40834d22e5e3fc748f060211879c056cd33; 5d5314d6795f3c1c0f415348ff8c51f7de042b77 up to, but not including, 33d9c814652b971461d1e30bead6792851c209e7; 5d5314d6795f3c1c0f415348ff8c51f7de042b77 up to, but not including, 107e825cc448b7834b31e8b1b3cf0f57426d46d5; 5d5314d6795f3c1c0f415348ff8c51f7de042b77 up to, but not including, f694da720dcf795dc3eb97bf76d220213f76aaa7; 5d5314d6795f3c1c0f415348ff8c51f7de042b77 up to, but not including, e9730744bf3af04cda23799029342aa3cddbc454; and 1 more rangesfb824a99e148ff272a53d71d84122728b5f00992, ddd2972d8e2dee3b33e8121669d55def59f0be8a, cfdc2fa4db57503bc6d3817240547c8ddc55fa96, f636a40834d22e5e3fc748f060211879c056cd33, 33d9c814652b971461d1e30bead6792851c209e7, 107e825cc448b7834b31e8b1b3cf0f57426d46d5
Linuxlinux_kernel1da177e4c3f4 up to, but not including, fb824a99e148; 1da177e4c3f4 up to, but not including, ddd2972d8e2d; 1da177e4c3f4 up to, but not including, cfdc2fa4db57; 1da177e4c3f4 up to, but not including, f636a40834d2; 1da177e4c3f4 up to, but not including, 33d9c814652b; 1da177e4c3f4 up to, but not including, 107e825cc448; 1da177e4c3f4 up to, but not including, f694da720dcf; 1da177e4c3f4 up to, but not including, e9730744bf3afb824a99e148, ddd2972d8e2d, cfdc2fa4db57, f636a40834d2, 33d9c814652b, 107e825cc448

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 3.18.4HighCNA
CVSS 3.17.8HighNVD
CVSS 3.17.8HighCISA (ADP)

Official description

In the Linux kernel, the following vulnerability has been resolved: kdb: Fix buffer overflow during tab-complete Currently, when the user attempts symbol completion with the Tab key, kdb will use strncpy() to insert the completed symbol into the command buffer. Unfortunately it passes the size of the source buffer rather than the destination to strncpy() with predictably horrible results. Most obviously if the command buffer is already full but cp, the cursor position, is in the middle of the buffer, then we will write past the end of the supplied buffer. Fix this by replacing the dubious strncpy() calls with memmove()/memcpy() calls plus explicit boundary checks to make sure we have enough space before we start moving characters around.

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

The underlying weakness: Buffer Copy without Checking Size of Input

The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output 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 Buffer Copy without Checking Size of Input vulnerabilities (CWE-120)

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 Buffer Copy without Checking Size of Input vulnerabilities

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