zephyr: Out-of-bounds Write
CVE-2026-13214 is a critical-severity out-of-bounds write vulnerability in zephyr from Zephyr Project, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 4.3.2, 4.4.2 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 0.9% chance of exploitation within 30 days, higher than 60% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update zephyr to 4.3.2 or 4.4.2, whichever matches your release line, or a later version.
- Read the advisory on github.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Zephyr Project | zephyr | 4.3.0 up to, but not including, 4.3.2; 4.4.0 up to, but not including, 4.4.2 | 4.3.2, 4.4.2 |
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
- NetworkCan be exploited remotely over a network, including the internet.
- 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:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by CNA (zephyrproject.org).
Official description
The OCPP 1.6 client in subsys/net/lib/ocpp/ocpp_j.c contains a stack buffer overflow in parse_getconfig_msg(). When handling a GetConfiguration request from the central system, the handler copied the attacker-controlled JSON "key" string into the caller's fixed 50-byte stack buffer (skey[CISTR50], declared in subsys/net/lib/ocpp/ocpp.c) using an unbounded strcpy(). The parsed key value points directly into the receive buffer, so its length is bounded only by the message size (CONFIG_OCPP_RECV_BUFFER_SIZE, default 2048). The GetConfiguration message is delivered over the WebSocket connection that the charge point opens to its configured central system. The reader thread ocpp_wsreader() reads the message into ui->recv_buf and dispatches it to parse_getconfig_msg() via the PDU function table. An attacker who controls the central system endpoint, or a man-in-the-middle on an unencrypted connection, can send a GetConfiguration request whose "key" field exceeds 50 bytes and overflow the reader thread's stack with attacker-chosen bytes. The consequence is a remotely triggerable stack smash on the OCPP reader thread: at minimum a denial of service, and plausibly remote code execution depending on build-time hardening such as stack canaries and MPU configuration. The fix replaces the strcpy() with a bounded strncpy(key, payload.key[0], CISTR50 - 1) followed by explicit NUL termination, matching the bounded copies already used by the sibling handlers.
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: none, automatable: yes, technical impact: total).
- 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
- 8.8 High severity
- 9.6 Critical severity
- 9.6 Critical severity
- 9.6 Critical severity
- 9.6 Critical severity
- 8.8 High severity
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