zephyr: Out-of-bounds Write
CVE-2026-10673 is a high-severity out-of-bounds write vulnerability in zephyr from Zephyr Project, with a CVSS 3.1 base score of 8.8 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 4.3.1, 4.4.1 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 0.42% 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 4.3.1 or 4.4.1, 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 |
|---|---|---|---|
| Zephyr Project | zephyr | 3.7.0 up to, but not including, 4.3.1; 4.4.0 up to, but not including, 4.4.1 | 4.3.1, 4.4.1 |
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
- 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
- HighData or code can be modified at will.
- 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:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 8.3 | High | CNA (zephyrproject.org) |
| CVSS 3.1 | 8.8 | High | NVD |
Official description
The Zephyr ADIN2111/ADIN1110 10BASE-T1S/T1L Ethernet driver (drivers/ethernet/eth_adin2111.c) reassembles received Ethernet frames in OPEN Alliance (OA) SPI mode by copying device-supplied 64-byte data chunks into a fixed static buffer ctx->buf of size CONFIG_ETH_ADIN2111_BUFFER_SIZE (default 1524 bytes). In eth_adin2111_oa_data_read(), each valid chunk was memcpy'd into ctx->buf[ctx->scur] and the write cursor scur advanced, with no check that scur + len stayed within the buffer. The number of chunks (up to 255, from the BUFSTS RCA field) and the per-chunk length are taken entirely from the frame data received off the wire; the cursor is only reset on a start-of-frame chunk. An attacker on the single-pair Ethernet segment can therefore send a frame whose reassembled size exceeds the configured buffer, causing the driver's RX offload thread to write attacker-controlled frame bytes past the end of the static buffer into adjacent driver/kernel memory (up to roughly 14.8 KB in the worst case). This is a remotely/adjacently reachable out-of-bounds write (CWE-787) that can corrupt memory and cause denial of service or potentially code execution. The defect was introduced when OA SPI support was added (commit 0ca8b0756b1) and shipped in releases v3.7.0 through v4.4.0. The fix adds a bounds check that drops the oversized frame and resets the cursor before the copy.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Out-of-bounds Write
The product writes data past the end, or before the beginning, of the intended buffer.
How developers prevent this class of flaw
- Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer. Be wary that a language's interface to native code may still be subject to overflows, even if the language itself is theoretically safe.
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Examples include the Safe C String Library (SafeStr) by Messier and Viega, and the Strsafe.h library from Microsoft. These libraries provide safer versions of overflow-prone string-handling functions.
- Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: poc, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Other vulnerabilities in zephyr
- 7.8 High severity
- 7.8 High severity
- 9.1 Critical severity
- 8.3 High severity
- 7.5 High severity
- 7.8 High severity
Recent Out-of-bounds Write 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
Spotted an error? Tell us.