CyberSecBulletin
CVE-2024-27395NVD status: Modified

Linux: Use After Free

Published Updated By the CyberSecBulletin desk

CVE-2024-27395 is a high-severity use after 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 2db9a8c0a01fa1c762c1e61a13c212c492752994, 589523cf0b384164e445dd5db8d5b1bf97982424, 35880c3fa6f8fe281a19975d2992644588ca33d3 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 0.24% 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 2db9a8c0a01fa1c762c1e61a13c212c492752994 or 589523cf0b384164e445dd5db8d5b1bf97982424 or 35880c3fa6f8fe281a19975d2992644588ca33d3 or 9048616553c65e750d43846f225843ed745ec0d4, whichever matches your release line, or a later version.
  2. Update RUGGEDCOM RST2428P to V3.1 or a later version.
  3. Update SCALANCE XCM-/XRM-/XCH-/XRH-300 family to V3.1 or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux11efd5cb04a184eea4f57b68ea63dddd463158d1 up to, but not including, 2db9a8c0a01fa1c762c1e61a13c212c492752994; 11efd5cb04a184eea4f57b68ea63dddd463158d1 up to, but not including, 589523cf0b384164e445dd5db8d5b1bf97982424; 11efd5cb04a184eea4f57b68ea63dddd463158d1 up to, but not including, 35880c3fa6f8fe281a19975d2992644588ca33d3; 11efd5cb04a184eea4f57b68ea63dddd463158d1 up to, but not including, 9048616553c65e750d43846f225843ed745ec0d4; 11efd5cb04a184eea4f57b68ea63dddd463158d1 up to, but not including, bca6fa2d9a9f560e6b89fd5190b05cc2f5d422c1; 11efd5cb04a184eea4f57b68ea63dddd463158d1 up to, but not including, eaa5e164a2110d2fb9e16c8a29e4501882235137; 11efd5cb04a184eea4f57b68ea63dddd463158d1 up to, but not including, edee0758747d7c219e29db9ed1d4eb33e8d32865; 11efd5cb04a184eea4f57b68ea63dddd463158d1 up to, but not including, 5ea7b72d4fac2fdbc0425cd8f2ea33abe95235b2; and 1 more ranges2db9a8c0a01fa1c762c1e61a13c212c492752994, 589523cf0b384164e445dd5db8d5b1bf97982424, 35880c3fa6f8fe281a19975d2992644588ca33d3, 9048616553c65e750d43846f225843ed745ec0d4, bca6fa2d9a9f560e6b89fd5190b05cc2f5d422c1, eaa5e164a2110d2fb9e16c8a29e4501882235137
SiemensRUGGEDCOM RST2428Pbefore V3.1V3.1
SiemensSCALANCE XC-300/XR-300/XC-400/XR-500WG/XR-500 familyNot specified in the recordNot stated
SiemensSCALANCE XCM-/XRM-/XCH-/XRH-300 familybefore V3.1V3.1
SiemensSIMATIC S7-1500 TM MFP - GNU/Linux subsystembefore V1.1.1V1.1.1
LinuxLinux Kernel4.18 up to, but not including, 4.19.313; 4.20 up to, but not including, 5.4.275; 5.5 up to, but not including, 5.10.216; 5.11 up to, but not including, 5.15.158; 5.16 up to, but not including, 6.1.90; 6.2 up to, but not including, 6.6.30; 6.7 up to, but not including, 6.8.9; 6.94.19.313, 5.4.275, 5.10.216, 5.15.158, 6.1.90, 6.6.30
DebianDebian Linux10.0Not 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: net: openvswitch: Fix Use-After-Free in ovs_ct_exit Since kfree_rcu, which is called in the hlist_for_each_entry_rcu traversal of ovs_ct_limit_exit, is not part of the RCU read critical section, it is possible that the RCU grace period will pass during the traversal and the key will be free. To prevent this, it should be changed to hlist_for_each_entry_safe.

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

The underlying weakness: Use After Free

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.

How developers prevent this class of flaw

  • Choose a language that provides automatic memory management.
  • When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.

More Use After Free vulnerabilities (CWE-416)

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 Use After Free vulnerabilities

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