Is there a public exploit for CVE-2026-79976?

No public exploit for CVE-2026-79976 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-2026-79976?

CVE-2026-79976 scores CVSS 7.1 (v3.1), rated high. EPSS puts the chance of exploitation in the next 30 days at 0.26%.

What does CVE-2026-79976 affect?

CVE-2026-79976 affects zephyrproject Zephyr.

7.1 High

The MCTP-over-I2C+GPIO target binding in subsys/pmci/mctp/mctpi2cgpiotarget.c emulates a small pseudo-register file, where the bus…

CVE-2026-79976

The MCTP-over-I2C+GPIO target binding in subsys/pmci/mctp/mctpi2cgpiotarget.c emulates a small pseudo-register file, where the bus controller first writes a register number and then writes or reads payload bytes. The selected register (b->regaddr) and the data-phase flag (b->rxtx) were never cleared when the controller issued an I2C STOP, so after a completed transfer the target still had a data register selected while the packet buffer that register refers to had already been consumed and set to NULL by mctpi2cgpiotargetstop(). A controller on the bus can re-enter the same branch of mctpi2cgpiotargetstop() with a NULL buffer using two ordinary transactions and no authentication: first a normal packet write to MCTPI2CGPIORXMSGADDR followed by STOP (which delivers and frees b->rxpkt), then a bare read transaction followed by STOP. The failing readrequested() call leaves the stale state untouched and the I2C driver still delivers the STOP callback, which then calls mctpbusrx() with a NULL packet. The symmetric case exists on the transmit side, where the stale MCTPI2CGPIOTXMSGADDR selection dereferences b->txpkt->end after b->txpkt has been cleared and additionally signals…

Assessment

CVSS: 7.1 (v3.1)
Severity: High
EPSS: 0.26% chance of exploitation in the next 30 days
Known exploited: Not listed in CISA KEV
Exploit availability: Nothing found in Exploit-DB, Metasploit, Nuclei or public PoC repositories
Published: 21 October 2026
Last updated: 4 November 2026
Affected: zephyrproject · Zephyr
Assigner: zephyr

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

At the source

EUVD (ENISA)

References

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