CyberSecBulletin
CVE-2024-49889NVD status: Modified

Linux: Use After Free

Published Updated By the CyberSecBulletin desk

CVE-2024-49889 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 b0cb4561fc4284d04e69c8a66c8504928ab2484e, 4999fed877bb64e3e7f9ab9996de2ca983c41928, 2eba3b0cc5b8de624918d21f32b5b8db59a90b39 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 0.26% 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 b0cb4561fc4284d04e69c8a66c8504928ab2484e or 4999fed877bb64e3e7f9ab9996de2ca983c41928 or 2eba3b0cc5b8de624918d21f32b5b8db59a90b39 or 34b2096380ba475771971a778a478661a791aa15, whichever matches your release line, or a later version.
  2. Update SIMATIC S7-1500 TM MFP - GNU/Linux subsystem to V1.1.1 or a later version.
  3. Update RUGGEDCOM RST2428P to V3.2 or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxdfe5080939ea4686b3414b5d970a9b26733c57a4 up to, but not including, b0cb4561fc4284d04e69c8a66c8504928ab2484e; dfe5080939ea4686b3414b5d970a9b26733c57a4 up to, but not including, 4999fed877bb64e3e7f9ab9996de2ca983c41928; dfe5080939ea4686b3414b5d970a9b26733c57a4 up to, but not including, 2eba3b0cc5b8de624918d21f32b5b8db59a90b39; dfe5080939ea4686b3414b5d970a9b26733c57a4 up to, but not including, 34b2096380ba475771971a778a478661a791aa15; dfe5080939ea4686b3414b5d970a9b26733c57a4 up to, but not including, 8b114f2cc7dd5d36729d040b68432fbd0f0a8868; dfe5080939ea4686b3414b5d970a9b26733c57a4 up to, but not including, d483c7cc1796bd6a80e7b3a8fd494996260f6b67; dfe5080939ea4686b3414b5d970a9b26733c57a4 up to, but not including, 4e2524ba2ca5f54bdbb9e5153bea00421ef653f5; 3.18b0cb4561fc4284d04e69c8a66c8504928ab2484e, 4999fed877bb64e3e7f9ab9996de2ca983c41928, 2eba3b0cc5b8de624918d21f32b5b8db59a90b39, 34b2096380ba475771971a778a478661a791aa15, 8b114f2cc7dd5d36729d040b68432fbd0f0a8868, d483c7cc1796bd6a80e7b3a8fd494996260f6b67
SiemensSIMATIC S7-1500 TM MFP - GNU/Linux subsystembefore V1.1.1V1.1.1
SiemensRUGGEDCOM RST2428Pbefore V3.2V3.2
SiemensSCALANCE XC-300/XR-300/XC-400/XR-500WG/XR-500 familybefore V3.2V3.2
SiemensSCALANCE XCM-/XRM-/XCH-/XRH-300 familybefore V3.2V3.2
LinuxLinux Kernelbefore 5.10.227; 5.11 up to, but not including, 5.15.168; 5.16 up to, but not including, 6.1.113; 6.2 up to, but not including, 6.6.55; 6.7 up to, but not including, 6.10.14; 6.11 up to, but not including, 6.11.35.10.227, 5.15.168, 6.1.113, 6.6.55, 6.10.14, 6.11.3

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
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: ext4: avoid use-after-free in ext4_ext_show_leaf() In ext4_find_extent(), path may be freed by error or be reallocated, so using a previously saved *ppath may have been freed and thus may trigger use-after-free, as follows: ext4_split_extent path = *ppath; ext4_split_extent_at(ppath) path = ext4_find_extent(ppath) ext4_split_extent_at(ppath) // ext4_find_extent fails to free path // but zeroout succeeds ext4_ext_show_leaf(inode, path) eh = path[depth].p_hdr // path use-after-free !!! Similar to ext4_split_extent_at(), we use *ppath directly as an input to ext4_ext_show_leaf(). Fix a spelling error by the way. Same problem in ext4_ext_handle_unwritten_extents(). Since 'path' is only used in ext4_ext_show_leaf(), remove 'path' and use *ppath directly. This issue is triggered only when EXT_DEBUG is defined and therefore does not affect functionality.

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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