CVE-2026-63915

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

nfc: hci: fix out-of-bounds read in HCP header parsing

Both nfc_hci_recv_from_llc() and nci_hci_data_received_cb() read packet->header from skb->data at function entry without first checking that the buffer holds at least one byte. A malicious NFC peer can send a 0-byte HCP frame that passes through the SHDLC layer and reaches these functions, causing an out-of-bounds heap read of packet->header. The same 0-byte frame, if queued as a non-final fragment, also causes the reassembly loop to underflow msg_len to UINT_MAX, triggering skb_over_panic() when the reassembled skb is written.

Fix this by adding a pskb_may_pull() check at the entry of each function before packet->header is first accessed. The existing pskb_may_pull() checks before the reassembled hcp_skb is cast to struct hcp_packet remain in place to guard the 2-byte HCP message header.

Weakness

The product reads data past the end, or before the beginning, of the intended buffer.

Affected Software

Potential Mitigations

• Assume all input is malicious. Use an “accept known good” input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
• When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, “boat” may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as “red” or “blue.”
• Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code’s environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
• To reduce the likelihood of introducing an out-of-bounds read, ensure that you validate and ensure correct calculations for any length argument, buffer size calculation, or offset. Be especially careful of relying on a sentinel (i.e. special character such as NUL) in untrusted inputs.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/540.html

References

• https://git.kernel.org/stable/c/1905f5ec3641b2b234bb63549c8ca11ab85466eb
• https://git.kernel.org/stable/c/22d41b176b9989efd21c3b2d3abf6728f05b9d9a
• https://git.kernel.org/stable/c/37382293f174b82a0616c8295e32b1fc8e13d1ed
• https://git.kernel.org/stable/c/83b1362edc9d6ae376c6f36da116e2c70f2e70a6
• https://git.kernel.org/stable/c/b99366d74b535d0cadb1ef73e04639415d9ff3b7
• https://git.kernel.org/stable/c/c4cc6b3b0013acb3ed0b2b60e57dfae98647fe98
• https://git.kernel.org/stable/c/ed6d5d97dad0334a7f43d218753429cbe2f70a4f
• https://git.kernel.org/stable/c/f040e590c035bfd9553fe79ee9585caf1b14d67b