Linux: Use After Free
CVE-2024-26749 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 cfa9abb5570c489dabf6f7fb3a066cc576fc8824, b40328eea93c75a5645891408010141a0159f643, 4e5c73b15d95452c1ba9c771dd013a3fbe052ff3 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.
High severity with no evidence of exploitation so far.
What to do
- Update Linux to cfa9abb5570c489dabf6f7fb3a066cc576fc8824 or b40328eea93c75a5645891408010141a0159f643 or 4e5c73b15d95452c1ba9c771dd013a3fbe052ff3 or 2134e9906e17b1e5284300fab547869ebacfd7d9, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.4.270 or 5.10.211 or 5.15.150 or 6.1.80, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 7733f6c32e36ff9d7adadf40001039bf219b1cbe up to, but not including, cfa9abb5570c489dabf6f7fb3a066cc576fc8824; 7733f6c32e36ff9d7adadf40001039bf219b1cbe up to, but not including, b40328eea93c75a5645891408010141a0159f643; 7733f6c32e36ff9d7adadf40001039bf219b1cbe up to, but not including, 4e5c73b15d95452c1ba9c771dd013a3fbe052ff3; 7733f6c32e36ff9d7adadf40001039bf219b1cbe up to, but not including, 2134e9906e17b1e5284300fab547869ebacfd7d9; 7733f6c32e36ff9d7adadf40001039bf219b1cbe up to, but not including, 29e42e1578a10c611b3f1a38f3229b2d664b5d16; 7733f6c32e36ff9d7adadf40001039bf219b1cbe up to, but not including, 9a07244f614bc417de527b799da779dcae780b5d; 7733f6c32e36ff9d7adadf40001039bf219b1cbe up to, but not including, cd45f99034b0c8c9cb346dd0d6407a95ca3d36f6; 5.4 | cfa9abb5570c489dabf6f7fb3a066cc576fc8824, b40328eea93c75a5645891408010141a0159f643, 4e5c73b15d95452c1ba9c771dd013a3fbe052ff3, 2134e9906e17b1e5284300fab547869ebacfd7d9, 29e42e1578a10c611b3f1a38f3229b2d664b5d16, 9a07244f614bc417de527b799da779dcae780b5d |
| Linux | Linux Kernel | 5.4 up to, but not including, 5.4.270; 5.5 up to, but not including, 5.10.211; 5.11 up to, but not including, 5.15.150; 5.16 up to, but not including, 6.1.80; 6.2 up to, but not including, 6.6.19; 6.7 up to, but not including, 6.7.7; 6.8 | 5.4.270, 5.10.211, 5.15.150, 6.1.80, 6.6.19, 6.7.7 |
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.
Official description
In the Linux kernel, the following vulnerability has been resolved: usb: cdns3: fixed memory use after free at cdns3_gadget_ep_disable() ... cdns3_gadget_ep_free_request(&priv_ep->endpoint, &priv_req->request); list_del_init(&priv_req->list); ... 'priv_req' actually free at cdns3_gadget_ep_free_request(). But list_del_init() use priv_req->list after it. [ 1542.642868][ T534] BUG: KFENCE: use-after-free read in __list_del_entry_valid+0x10/0xd4 [ 1542.642868][ T534] [ 1542.653162][ T534] Use-after-free read at 0x000000009ed0ba99 (in kfence-#3): [ 1542.660311][ T534] __list_del_entry_valid+0x10/0xd4 [ 1542.665375][ T534] cdns3_gadget_ep_disable+0x1f8/0x388 [cdns3] [ 1542.671571][ T534] usb_ep_disable+0x44/0xe4 [ 1542.675948][ T534] ffs_func_eps_disable+0x64/0xc8 [ 1542.680839][ T534] ffs_func_set_alt+0x74/0x368 [ 1542.685478][ T534] ffs_func_disable+0x18/0x28 Move list_del_init() before cdns3_gadget_ep_free_request() to resolve this problem.
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.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/2134e9906e17b1e5284300fab547869ebacfd7d9
- git.kernel.org/stable/c/29e42e1578a10c611b3f1a38f3229b2d664b5d16
- git.kernel.org/stable/c/4e5c73b15d95452c1ba9c771dd013a3fbe052ff3
- git.kernel.org/stable/c/9a07244f614bc417de527b799da779dcae780b5d
- git.kernel.org/stable/c/b40328eea93c75a5645891408010141a0159f643
- git.kernel.org/stable/c/cd45f99034b0c8c9cb346dd0d6407a95ca3d36f6
- git.kernel.org/stable/c/cfa9abb5570c489dabf6f7fb3a066cc576fc8824
Other references
Recent Use After Free vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
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