CyberSecBulletin
CVE-2024-56766NVD status: Modified

Linux: Double Free

Published Updated By the CyberSecBulletin desk

CVE-2024-56766 is a high-severity double free 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 ca9818554b0f33e87f38e4bfa2dac056692d46cc, 1562871ef613fa9492aa0310933eff785166a90e, 3d825a241e65f7e3072978729e79d735ec40b80e 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 0.22% 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 ca9818554b0f33e87f38e4bfa2dac056692d46cc or 1562871ef613fa9492aa0310933eff785166a90e or 3d825a241e65f7e3072978729e79d735ec40b80e or 6ea15205d7e2b811fbbdf79783f686f58abfb4b7, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 4.20 or 5.5 or 5.11 or 5.16, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux22fbbc37edb840fd420fadf670366be9bf028426 up to, but not including, ca9818554b0f33e87f38e4bfa2dac056692d46cc; 54cb5fa850f9306d84e49a3db44b7a7eb5536cd1 up to, but not including, 1562871ef613fa9492aa0310933eff785166a90e; 5fe7709251e334cc27618473299c48340cecd3c8 up to, but not including, 3d825a241e65f7e3072978729e79d735ec40b80e; 24cbc37e837fd9e31e5024480b779207d1d99f1d up to, but not including, 6ea15205d7e2b811fbbdf79783f686f58abfb4b7; f1290871c8aaeb13029390a2b6e5c05733a1be6f up to, but not including, dd45c87782738715d5e7c167f8dabf0814a7394a; 8ac19ec818c548c5788da5926dcc8af96fad4bb1 up to, but not including, d2f090ea57f8d6587e09d4066f740a8617767b3d; 6d734f1bfc336aaea91313a5632f2f197608fadd up to, but not including, d8e4771f99c0400a1873235704b28bb803c83d17; 2014fcea19ec27df033359a0f42db0e8ed4290a8; and 9 more rangesca9818554b0f33e87f38e4bfa2dac056692d46cc, 1562871ef613fa9492aa0310933eff785166a90e, 3d825a241e65f7e3072978729e79d735ec40b80e, 6ea15205d7e2b811fbbdf79783f686f58abfb4b7, dd45c87782738715d5e7c167f8dabf0814a7394a, d2f090ea57f8d6587e09d4066f740a8617767b3d
LinuxLinux Kernel4.19.325 up to, but not including, 4.20; 5.4.287 up to, but not including, 5.5; 5.10.231 up to, but not including, 5.11; 5.15.174 up to, but not including, 5.16; 6.1.120 up to, but not including, 6.1.123; 6.6.64 up to, but not including, 6.6.69; 6.11.11 up to, but not including, 6.12; 6.12.2 up to, but not including, 6.12.8; and 1 more ranges4.20, 5.5, 5.11, 5.16, 6.1.123, 6.6.69

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: mtd: rawnand: fix double free in atmel_pmecc_create_user() The "user" pointer was converted from being allocated with kzalloc() to being allocated by devm_kzalloc(). Calling kfree(user) will lead to a double free.

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

The underlying weakness: Double Free

The product calls free() twice on the same memory address.

How developers prevent this class of flaw

  • Choose a language that provides automatic memory management.
  • Ensure that each allocation is freed only once. After freeing a chunk, set the pointer to NULL to ensure the pointer cannot be freed again. In complicated error conditions, be sure that clean-up routines respect the state of allocation properly. If the language is object oriented, ensure that object destructors delete each chunk of memory only once.
  • Use a static analysis tool to find double free instances.

More Double Free vulnerabilities (CWE-415)

Timeline

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

References

Recent Double Free vulnerabilities

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