CyberSecBulletin
CVE-2024-49960NVD status: Modified

Linux: Use After Free

Published Updated By the CyberSecBulletin desk

CVE-2024-49960 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 7aac0c17a8cdf4a3236991c1e60435c6a984076c, 22e9b83f0f33bc5a7a3181769d1dccbf021f5b04, cf3196e5e2f36cd80dab91ffae402e13935724bc 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 0.29% 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 7aac0c17a8cdf4a3236991c1e60435c6a984076c or 22e9b83f0f33bc5a7a3181769d1dccbf021f5b04 or cf3196e5e2f36cd80dab91ffae402e13935724bc or 9203817ba46ebba7c865c8de2aba399537b6e891, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.10.237 or 5.15.181 or 6.1.118 or 6.6.55, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux5e4f5138bd8522ebe231a137682d3857209a2c07 up to, but not including, 7aac0c17a8cdf4a3236991c1e60435c6a984076c; 618f003199c6188e01472b03cdbba227f1dc5f24 up to, but not including, 22e9b83f0f33bc5a7a3181769d1dccbf021f5b04; 618f003199c6188e01472b03cdbba227f1dc5f24 up to, but not including, cf3196e5e2f36cd80dab91ffae402e13935724bc; 618f003199c6188e01472b03cdbba227f1dc5f24 up to, but not including, 9203817ba46ebba7c865c8de2aba399537b6e891; 618f003199c6188e01472b03cdbba227f1dc5f24 up to, but not including, fa78fb51d396f4f2f80f8e96a3b1516f394258be; 618f003199c6188e01472b03cdbba227f1dc5f24 up to, but not including, b85569585d0154d4db1e4f9e3e6a4731d407feb0; 618f003199c6188e01472b03cdbba227f1dc5f24 up to, but not including, 0ce160c5bdb67081a62293028dc85758a8efb22a; cecfdb9cf9a700d1037066173abac0617f6788df; and 5 more ranges7aac0c17a8cdf4a3236991c1e60435c6a984076c, 22e9b83f0f33bc5a7a3181769d1dccbf021f5b04, cf3196e5e2f36cd80dab91ffae402e13935724bc, 9203817ba46ebba7c865c8de2aba399537b6e891, fa78fb51d396f4f2f80f8e96a3b1516f394258be, b85569585d0154d4db1e4f9e3e6a4731d407feb0
DebianDebian Linux11.0Not stated
LinuxLinux Kernelbefore 5.10.237; 5.11 up to, but not including, 5.15.181; 5.16 up to, but not including, 6.1.118; 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, 6.11.35.10.237, 5.15.181, 6.1.118, 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: fix timer use-after-free on failed mount Syzbot has found an ODEBUG bug in ext4_fill_super The del_timer_sync function cancels the s_err_report timer, which reminds about filesystem errors daily. We should guarantee the timer is no longer active before kfree(sbi). When filesystem mounting fails, the flow goes to failed_mount3, where an error occurs when ext4_stop_mmpd is called, causing a read I/O failure. This triggers the ext4_handle_error function that ultimately re-arms the timer, leaving the s_err_report timer active before kfree(sbi) is called. Fix the issue by canceling the s_err_report timer after calling ext4_stop_mmpd.

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

Third-party and government advisories

Recent Use After Free vulnerabilities

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