CVE-2026-31622NFC: digital: Bounds check NFC-A cascade depth in SDD response handler

Official description

In the Linux kernel, the following vulnerability has been resolved: NFC: digital: Bounds check NFC-A cascade depth in SDD response handler The NFC-A anti-collision cascade in digital_in_recv_sdd_res() appends 3 or 4 bytes to target->nfcid1 on each round, but the number of cascade rounds is controlled entirely by the peer device. The peer sets the cascade tag in the SDD_RES (deciding 3 vs 4 bytes) and the cascade-incomplete bit in the SEL_RES (deciding whether another round follows). ISO 14443-3 limits NFC-A to three cascade levels and target->nfcid1 is sized accordingly (NFC_NFCID1_MAXSIZE = 10), but nothing in the driver actually enforces this. This means a malicious peer can keep the cascade running, writing past the heap-allocated nfc_target with each round. Fix this by rejecting the response when the accumulated UID would exceed the buffer. Commit e329e71013c9 ("NFC: nci: Bounds check struct nfc_target arrays") fixed similar missing checks against the same field on the NCI path.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/9ba6bb09e00b922d902f684f575779e5433fe6e3
• https://git.kernel.org/stable/c/f83b399aa05a0712e3b1569a30d3d90b3533d2ef
• https://git.kernel.org/stable/c/20663102c14566e900e1d2f679e30b7f1694f387
• https://git.kernel.org/stable/c/2819f34e08bdffb6f06a51c67948ec5737fb166a
• https://git.kernel.org/stable/c/1bec5698b55aa2be5c3b983dba657c01d0fd3dbc
• https://git.kernel.org/stable/c/5a59bf70c38ee1eb4be03bab830bbc3a6f0bd1f1
• https://git.kernel.org/stable/c/8d9d9bf3565271ca7ab9c716a94e87296177e7ba
• https://git.kernel.org/stable/c/cc024a3de265ef6c58957f4990eccb9f806208cb
• https://git.kernel.org/stable/c/46ce8be2ced389bccd84bcc04a12cf2f4d0c22d1
• https://cert-portal.siemens.com/productcert/html/ssa-784472.html