CVE-2026-98438
Description
In the Linux kernel, the following vulnerability has been resolved: mptcp: options: fix uninit-value in mptcp_write_data_fin When sending a DATA_FIN without data, and because the DATA_FIN occupies 1 octet of the connection-level sequence space [1], it is then required to add a DSS mapping with specific values. If the checksum has been negotiated, it also needs to be computed, and included in the outgoing packet, and thus the initial csum data needs to be reset to 0 as well. This is no longer the case since commit cfcceb7a39fc ("tcp: shrink per-packet memset in __tcp_transmit_skb()"), because the whole ext_copy structure is no longer zeroed by default. This seems to be the only case where use_map is changed and set afterwards, so initialising the csum field only in this case, along with other fields for this specific case.
How to fix
- Linux Linux9a682067dd7b9dce6b94a0a05661dcc921446402, b110f1dd6cb6a9930503354a01a315e0a821eaa7 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| Linux Linux | cfcceb7a39fc10a6f896af8229bf81d96acb22cc ≤ v < 9a682067dd7b9dce6b94a0a05661dcc921446402, cfcceb7a39fc10a6f896af8229bf81d96acb22cc ≤ v < b110f1dd6cb6a9930503354a01a315e0a821eaa7, 7.1 | 9a682067dd7b9dce6b94a0a05661dcc921446402, b110f1dd6cb6a9930503354a01a315e0a821eaa7 |
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