Zephyr: Out-of-bounds Read
CVE-2026-5071 is a high-severity out-of-bounds read vulnerability in Zephyr from Zephyrproject-rtos, 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 3.7.2, 4.2.2, 4.3.1 as the first without the flaw, so updating Zephyr to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.17% 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 Zephyr to 3.7.2 or 4.2.2 or 4.3.1, whichever matches your release line, or a later version.
- Read the advisory on github.com for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Zephyrproject-rtos | Zephyr | before 3.7.2; 4.0.0 up to, but not including, 4.2.2; 4.3.0 up to, but not including, 4.3.1 | 3.7.2, 4.2.2, 4.3.1 |
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 system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 6.1 | Medium | CNA (zephyrproject.org) |
| CVSS 3.1 | 7.8 | High | NVD |
Official description
The SocketCAN implementation validates the length of a user-provided buffer containing a socketcan_frame object using only a NET_ASSERT statement in zcan_sendto_ctx() before dereferencing it in socketcan_to_can_frame(). In production builds where assertions are disabled, a userspace application that controls the length passed to a sendto syscall can supply an incomplete or truncated frame, causing socketcan_to_can_frame() to dereference fields beyond the end of the buffer. This results in an out-of-bounds read that can cause denial-of-service crashes or, because the parsed frame contents are transmitted on the network, leak adjacent memory.
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
Other vulnerabilities in Zephyr
- 7.5 High severity
- 8.8 High severity
- 9.8 Critical severity
- 8.8 High severity
- 7.8 High severity
- 9.8 Critical severity
Recent Out-of-bounds Read vulnerabilities
- 7.8 High severity
- 8.3 High severity
- 8.8 High severity
- 8.8 High severity
- 8.3 High severity
- 8.3 High severity
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