Is there a public exploit for CVE-2026-90834?

No public exploit for CVE-2026-90834 was found in Exploit-DB, Metasploit, Nuclei templates or public proof-of-concept repositories. That is an absence of evidence rather than proof that none exists.

How severe is CVE-2026-90834?

CVE-2026-90834 scores CVSS 5.5 (v3.1), rated medium.

What does CVE-2026-90834 affect?

CVE-2026-90834 affects zephyrproject Zephyr.

5.5 Medium

The user-mode syscall verifiers for the 16-bit ("wide data") UART API in drivers/serial/uarthandlers.c validated the wrong driver operation.

CVE-2026-90834

The user-mode syscall verifiers for the 16-bit ("wide data") UART API in drivers/serial/uarthandlers.c validated the wrong driver operation. zvrfyuartpolloutu16(), zvrfyuarttxu16() and zvrfyuartrxenableu16() each ran KSYSCALLDRIVERUART() against the 8-bit op (pollout, tx, rxenable) rather than the 16-bit op that the corresponding implementation dereferences (polloutu16, txu16, rxenableu16). zimpluartpolloutu16(), zimpluarttxu16() and zimpluartrxenableu16() in include/zephyr/drivers/uart/uartinternal.h call their op unconditionally, with no NULL guard of their own, because the verifier is supposed to have established that the op exists. CONFIGUARTWIDEDATA is an application-selectable option that no driver selects, and only a handful of the serial drivers in the tree implement any u16 operation; every other driver leaves those struct uartdriverapi members NULL while still providing the 8-bit ops the old check inspected. In a build with CONFIGUSERSPACE and CONFIGUARTWIDEDATA (plus CONFIGUARTASYNCAPI for the uarttxu16() and uartrxenableu16() variants), an unprivileged user-mode thread that legitimately holds access to such a UART device object can invoke the u16 syscall: the object,…

Assessment

CVSS: 5.5 (v3.1)
Severity: Medium
Known exploited: Not listed in CISA KEV
Exploit availability: Nothing found in Exploit-DB, Metasploit, Nuclei or public PoC repositories
Published: 10 November 2026
Last updated: 10 November 2026
Affected: zephyrproject · Zephyr
Assigner: zephyr

CVSS vectorCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

At the source

EUVD (ENISA)

References

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