CVE-2026-98582

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

nfc: st21nfca: validate received frame size

st21nfca_hci_i2c_repack() trims a received frame at its EOF marker

before removing byte stuffing. It then assumes the truncated frame

contains the LLC header and two CRC bytes, and it unconditionally reads

the byte after an escape marker.

A malformed frame can place EOF immediately after the start marker or can

end its data portion with an escape marker. The former leaves too few

bytes for check_crc(), while the latter makes the unstuffing loop read past

the current skb length.

Require the minimum framing bytes both before and after unstuffing. Use

separate input and output cursors while removing byte stuffing, and reject

an escape marker without its encoded byte. This keeps malformed frames

within the received frame boundary before CRC processing.

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References