CyberSecBulletin
CVE-2024-46800NVD status: Modified

Linux: Use After Free

Published Updated By the CyberSecBulletin desk

CVE-2024-46800 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 f0bddb4de043399f16d1969dad5ee5b984a64e7b, 295ad5afd9efc5f67b86c64fce28fb94e26dc4c9, 98c75d76187944296068d685dfd8a1e9fd8c4fdc 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 0.3% 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 f0bddb4de043399f16d1969dad5ee5b984a64e7b or 295ad5afd9efc5f67b86c64fce28fb94e26dc4c9 or 98c75d76187944296068d685dfd8a1e9fd8c4fdc or 14f91ab8d391f249b845916820a56f42cf747241, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 4.19.322 or 5.4.284 or 5.10.226 or 5.15.167, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux50612537e9ab29693122fab20fc1eed235054ffe up to, but not including, f0bddb4de043399f16d1969dad5ee5b984a64e7b; 50612537e9ab29693122fab20fc1eed235054ffe up to, but not including, 295ad5afd9efc5f67b86c64fce28fb94e26dc4c9; 50612537e9ab29693122fab20fc1eed235054ffe up to, but not including, 98c75d76187944296068d685dfd8a1e9fd8c4fdc; 50612537e9ab29693122fab20fc1eed235054ffe up to, but not including, 14f91ab8d391f249b845916820a56f42cf747241; 50612537e9ab29693122fab20fc1eed235054ffe up to, but not including, db2c235682913a63054e741fe4e19645fdf2d68e; 50612537e9ab29693122fab20fc1eed235054ffe up to, but not including, dde33a9d0b80aae0c69594d1f462515d7ff1cb3d; 50612537e9ab29693122fab20fc1eed235054ffe up to, but not including, 32008ab989ddcff1a485fa2b4906234c25dc5cd6; 50612537e9ab29693122fab20fc1eed235054ffe up to, but not including, 3b3a2a9c6349e25a025d2330f479bc33a6ccb54a; and 1 more rangesf0bddb4de043399f16d1969dad5ee5b984a64e7b, 295ad5afd9efc5f67b86c64fce28fb94e26dc4c9, 98c75d76187944296068d685dfd8a1e9fd8c4fdc, 14f91ab8d391f249b845916820a56f42cf747241, db2c235682913a63054e741fe4e19645fdf2d68e, dde33a9d0b80aae0c69594d1f462515d7ff1cb3d
LinuxLinux Kernel3.3 up to, but not including, 4.19.322; 4.20 up to, but not including, 5.4.284; 5.5 up to, but not including, 5.10.226; 5.11 up to, but not including, 5.15.167; 5.16 up to, but not including, 6.1.110; 6.2 up to, but not including, 6.6.51; 6.7 up to, but not including, 6.10.10; 6.114.19.322, 5.4.284, 5.10.226, 5.15.167, 6.1.110, 6.6.51

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: sch/netem: fix use after free in netem_dequeue If netem_dequeue() enqueues packet to inner qdisc and that qdisc returns __NET_XMIT_STOLEN. The packet is dropped but qdisc_tree_reduce_backlog() is not called to update the parent's q.qlen, leading to the similar use-after-free as Commit e04991a48dbaf382 ("netem: fix return value if duplicate enqueue fails") Commands to trigger KASAN UaF: ip link add type dummy ip link set lo up ip link set dummy0 up tc qdisc add dev lo parent root handle 1: drr tc filter add dev lo parent 1: basic classid 1:1 tc class add dev lo classid 1:1 drr tc qdisc add dev lo parent 1:1 handle 2: netem tc qdisc add dev lo parent 2: handle 3: drr tc filter add dev lo parent 3: basic classid 3:1 action mirred egress redirect dev dummy0 tc class add dev lo classid 3:1 drr ping -c1 -W0.01 localhost # Trigger bug tc class del dev lo classid 1:1 tc class add dev lo classid 1:1 drr ping -c1 -W0.01 localhost # UaF

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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