Linux: Out-of-bounds Read
CVE-2026-31771 is a high-severity out-of-bounds read vulnerability in Linux, with a CVSS 3.1 base score of 8.1 out of 10. It can be exploited from the same local network by an unauthenticated attacker, without any action from a user. The record lists versions fbea63d0d301edd4a42f4390b49b8519d78b802d, 1e4b738dd0d0f7b237686167706badad9d30649c, ac7889b0fe441e4ef892c40b1d002e91f93fa4ae 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 0.32% 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 fbea63d0d301edd4a42f4390b49b8519d78b802d or 1e4b738dd0d0f7b237686167706badad9d30649c or ac7889b0fe441e4ef892c40b1d002e91f93fa4ae or dbc8b8d33c9e19e17e8b8b1361bbb46e2983f5f2, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.19.12 or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 2f20216c1d6fe17c1a224f658be0dc6fab2269c7 up to, but not including, fbea63d0d301edd4a42f4390b49b8519d78b802d; 2f20216c1d6fe17c1a224f658be0dc6fab2269c7 up to, but not including, 1e4b738dd0d0f7b237686167706badad9d30649c; 2f20216c1d6fe17c1a224f658be0dc6fab2269c7 up to, but not including, ac7889b0fe441e4ef892c40b1d002e91f93fa4ae; 2f20216c1d6fe17c1a224f658be0dc6fab2269c7 up to, but not including, dbc8b8d33c9e19e17e8b8b1361bbb46e2983f5f2; 2f20216c1d6fe17c1a224f658be0dc6fab2269c7 up to, but not including, 86c8d07a64d553c41e213b52650020010f9ef23e; 2f20216c1d6fe17c1a224f658be0dc6fab2269c7 up to, but not including, 2b2bf47cd75518c36fa2d41380e4a40641cc89cd; 5.10 | fbea63d0d301edd4a42f4390b49b8519d78b802d, 1e4b738dd0d0f7b237686167706badad9d30649c, ac7889b0fe441e4ef892c40b1d002e91f93fa4ae, dbc8b8d33c9e19e17e8b8b1361bbb46e2983f5f2, 86c8d07a64d553c41e213b52650020010f9ef23e, 2b2bf47cd75518c36fa2d41380e4a40641cc89cd |
| Linux | Linux Kernel | 5.10 up to, but not including, 6.19.12; 7.0 | 6.19.12 |
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
- AdjacentThe attacker must be on the same local network segment.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- 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:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H. Scored by CNA.
Official description
In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_event: move wake reason storage into validated event handlers hci_store_wake_reason() is called from hci_event_packet() immediately after stripping the HCI event header but before hci_event_func() enforces the per-event minimum payload length from hci_ev_table. This means a short HCI event frame can reach bacpy() before any bounds check runs. Rather than duplicating skb parsing and per-event length checks inside hci_store_wake_reason(), move wake-address storage into the individual event handlers after their existing event-length validation has succeeded. Convert hci_store_wake_reason() into a small helper that only stores an already-validated bdaddr while the caller holds hci_dev_lock(). Use the same helper after hci_event_func() with a NULL address to preserve the existing unexpected-wake fallback semantics when no validated event handler records a wake address. Annotate the helper with __must_hold(&hdev->lock) and add lockdep_assert_held(&hdev->lock) so future call paths keep the lock contract explicit. Call the helper from hci_conn_request_evt(), hci_conn_complete_evt(), hci_sync_conn_complete_evt(), le_conn_complete_evt(), hci_le_adv_report_evt(), hci_le_ext_adv_report_evt(), hci_le_direct_adv_report_evt(), hci_le_pa_sync_established_evt(), and hci_le_past_received_evt().
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Out-of-bounds Read
The product reads data past the end, or before the beginning, of the intended buffer.
How developers prevent this class of flaw
- Use a language that provides appropriate memory abstractions.
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
Other references
Recent Out-of-bounds Read vulnerabilities
- 8.1 High severity
- 8.8 High severity
- 7.1 High severity
- 7.3 High severity
- 7.1 High severity
- 7.1 High severity
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