Is there a public exploit for CVE-2026-77685?

No public exploit for CVE-2026-77685 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-2026-77685?

CVE-2026-77685 scores CVSS 8.3 (v3.1), rated high.

What does CVE-2026-77685 affect?

CVE-2026-77685 affects zephyrproject Zephyr.

8.3 High

The RFCOMM multiplexer control-channel handler in subsys/bluetooth/host/classic/rfcomm.c computed the echo length for a BTRFCOMMTEST…

CVE-2026-77685

The RFCOMM multiplexer control-channel handler in subsys/bluetooth/host/classic/rfcomm.c computed the echo length for a BTRFCOMMTEST command as buf->len - 1 and passed it to rfcommsendtest(), whose length parameter is a uint8t. A malformed but FCS-valid UIH frame on DLCI 0 can leave buf->len == 0 after rfcommhandlemsg() pulls the two-byte MCC header, so buf->len - 1 underflows and narrows to 255. rfcommsendtest() then copies 255 bytes out of a receive buffer that holds no remaining valid data, and appends them to an outgoing L2CAP PDU allocated with only CONFIGBTL2CAPTXMTU (253 by default for CONFIGBTCLASSIC) bytes of tailroom. The source read runs past the end of the ACL receive buffer into adjacent buffers of the same netbuf pool, and the destination copy overruns the transmit buffer by about eight bytes; netbufaddmem() performs no runtime bounds check in ordinary builds, where the underlying ASSERTNOMSG() is compiled out. The trigger is a single five-byte RFCOMM frame on the multiplexer control channel, which is processed as soon as the L2CAP channel for PSM 3 is established — before any DLC exists and independent of RFCOMM session state. btrfcomminit() registers that L2CAP…

Assessment

CVSS: 8.3 (v3.1)
Severity: High
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:A/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:H

At the source

EUVD (ENISA)

References

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