CVE-2026-63867

Summary

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

mptcp: close TOCTOU race while computing rcv_wnd

The MPTCP output path access locklessly the MPTCP-level ack_seq in multiple times, using possibly different values for the data_ack in the DSS option and to compute the announced rcv wnd for the same packet.

Refactor the cote to avoid inconsistencies which may confuse the peer. Also ensure that the MPTCP level rcv wnd is updated only when the egress packet actually contains a DSS ack.

Affected Software

VendorProductVersion RangeStatus
LinuxLinuxfa3fe2b150316b294f2c662653501273ff25bba8 < 301a33fd590c408a05c5df800e0cc1e6a8a2f8f8affected
LinuxLinuxfa3fe2b150316b294f2c662653501273ff25bba8 < 68364963e5baf03f16b4420292291f75c8f66497affected
LinuxLinuxfa3fe2b150316b294f2c662653501273ff25bba8 < 907ac6b1658e0277f979fcdfae2a753b495c1510affected
LinuxLinuxfa3fe2b150316b294f2c662653501273ff25bba8 < c4f4cf60797974873dbc8e100144682a6f2f861faffected
LinuxLinuxfa3fe2b150316b294f2c662653501273ff25bba8 < 3b8cbba7c0ed31189c89f90be247b8973ffa79efaffected
LinuxLinuxfa3fe2b150316b294f2c662653501273ff25bba8 < 8f4f0a157e8436a05bf8c3670b24dbc258911c43affected
LinuxLinuxfa3fe2b150316b294f2c662653501273ff25bba8 < 8ab24fdebc369c0dfb90f82c1650b1e66662bb45affected
LinuxLinux5.11affected
LinuxLinux0 < 5.11unaffected
LinuxLinux5.15.210 <= 5.15.*unaffected
LinuxLinux6.1.176 <= 6.1.*unaffected
LinuxLinux6.6.143 <= 6.6.*unaffected
LinuxLinux6.12.94 <= 6.12.*unaffected
LinuxLinux6.18.36 <= 6.18.*unaffected
LinuxLinux7.0.13 <= 7.0.*unaffected
LinuxLinux7.1 <= *unaffected

Weaknesses

References