CyberSecBulletin
CVE-2024-38538NVD status: Modified

Linux: Use of Uninitialized Resource

Published Updated By the CyberSecBulletin desk

CVE-2024-38538 is a high-severity use of uninitialized resource vulnerability in Linux, with a CVSS 3.1 base score of 7.1 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 3e01fc3c66e65d9afe98f1489047a1b2dd8741ca, b2b7c43cd32080221bb233741bd6011983fe7c11, 82090f94c723dab724b1c32db406091d40448a17 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 0.28% 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 3e01fc3c66e65d9afe98f1489047a1b2dd8741ca or b2b7c43cd32080221bb233741bd6011983fe7c11 or 82090f94c723dab724b1c32db406091d40448a17 or c964429ef53f42098a6545a5dabeb1441c1e821d, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 6.1.93 or 6.6.33 or 6.8.12 or 6.9.3, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 3e01fc3c66e65d9afe98f1489047a1b2dd8741ca; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, b2b7c43cd32080221bb233741bd6011983fe7c11; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 82090f94c723dab724b1c32db406091d40448a17; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, c964429ef53f42098a6545a5dabeb1441c1e821d; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 28126b83f86ab9cc7936029c2dff845d3dcedba2; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 1abb371147905ba250b4cc0230c4be7e90bea4d5; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, f482fd4ce919836a49012b2d31b00fc36e2488f2; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 5b5d669f569807c7ab07546e73c0741845a2547a; and 2 more ranges3e01fc3c66e65d9afe98f1489047a1b2dd8741ca, b2b7c43cd32080221bb233741bd6011983fe7c11, 82090f94c723dab724b1c32db406091d40448a17, c964429ef53f42098a6545a5dabeb1441c1e821d, 28126b83f86ab9cc7936029c2dff845d3dcedba2, 1abb371147905ba250b4cc0230c4be7e90bea4d5
LinuxLinux Kernel2.6.12 up to, but not including, 6.1.93; 6.2 up to, but not including, 6.6.33; 6.7 up to, but not including, 6.8.12; 6.9 up to, but not including, 6.9.36.1.93, 6.6.33, 6.8.12, 6.9.3

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
NoneNothing can be modified.
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:N/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.17.3HighCNA
CVSS 3.17.1HighNVD

Official description

In the Linux kernel, the following vulnerability has been resolved: net: bridge: xmit: make sure we have at least eth header len bytes syzbot triggered an uninit value[1] error in bridge device's xmit path by sending a short (less than ETH_HLEN bytes) skb. To fix it check if we can actually pull that amount instead of assuming. Tested with dropwatch: drop at: br_dev_xmit+0xb93/0x12d0 [bridge] (0xffffffffc06739b3) origin: software timestamp: Mon May 13 11:31:53 2024 778214037 nsec protocol: 0x88a8 length: 2 original length: 2 drop reason: PKT_TOO_SMALL [1] BUG: KMSAN: uninit-value in br_dev_xmit+0x61d/0x1cb0 net/bridge/br_device.c:65 br_dev_xmit+0x61d/0x1cb0 net/bridge/br_device.c:65 __netdev_start_xmit include/linux/netdevice.h:4903 [inline] netdev_start_xmit include/linux/netdevice.h:4917 [inline] xmit_one net/core/dev.c:3531 [inline] dev_hard_start_xmit+0x247/0xa20 net/core/dev.c:3547 __dev_queue_xmit+0x34db/0x5350 net/core/dev.c:4341 dev_queue_xmit include/linux/netdevice.h:3091 [inline] __bpf_tx_skb net/core/filter.c:2136 [inline] __bpf_redirect_common net/core/filter.c:2180 [inline] __bpf_redirect+0x14a6/0x1620 net/core/filter.c:2187 ____bpf_clone_redirect net/core/filter.c:2460 [inline] bpf_clone_redirect+0x328/0x470 net/core/filter.c:2432 ___bpf_prog_run+0x13fe/0xe0f0 kernel/bpf/core.c:1997 __bpf_prog_run512+0xb5/0xe0 kernel/bpf/core.c:2238 bpf_dispatcher_nop_func include/linux/bpf.h:1234 [inline] __bpf_prog_run include/linux/filter.h:657 [inline] bpf_prog_run include/linux/filter.h:664 [inline] bpf_test_run+0x499/0xc30 net/bpf/test_run.c:425 bpf_prog_test_run_skb+0x14ea/0x1f20 net/bpf/test_run.c:1058 bpf_prog_test_run+0x6b7/0xad0 kernel/bpf/syscall.c:4269 __sys_bpf+0x6aa/0xd90 kernel/bpf/syscall.c:5678 __do_sys_bpf kernel/bpf/syscall.c:5767 [inline] __se_sys_bpf kernel/bpf/syscall.c:5765 [inline] __x64_sys_bpf+0xa0/0xe0 kernel/bpf/syscall.c:5765 x64_sys_call+0x96b/0x3b50 arch/x86/include/generated/asm/syscalls_64.h:322 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f

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

The underlying weakness: Use of Uninitialized Resource

The product uses or accesses a resource that has not been initialized.

How developers prevent this class of flaw

  • Explicitly initialize the resource before use. If this is performed through an API function or standard procedure, follow all required steps.
  • Pay close attention to complex conditionals that affect initialization, since some branches might not perform the initialization.
  • Avoid race conditions (CWE-362) during initialization routines.

More Use of Uninitialized Resource vulnerabilities (CWE-908)

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 of Uninitialized Resource vulnerabilities

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