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Vulnerability · Published Jul 19, 2026 · Assigned by Linux

CVE-2026-63867mptcp: close TOCTOU race while computing rcv_wnd

High 8.2

In plain English

A high-severity race condition in Linux from Linux. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 20% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)8.2High
Exploit odds (30 days)0.3%top 80.1% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

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 packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12linux6.1.176-1DEBIAN-CVE-2026-63867
Debian:13linux6.12.94-1DEBIAN-CVE-2026-63867
Debian:14linux7.0.13-1DEBIAN-CVE-2026-63867
Ubuntu:22.04:LTSlinux5.15.0-198.208UBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux6.8.0-146.146UBUNTU-CVE-2026-63867
Ubuntu:26.04:LTSlinux7.0.0-31.31UBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-allwinner-5.19no fix listedUBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-aws5.15.0-1117.124UBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-aws6.8.0-1066.69UBUNTU-CVE-2026-63867
Ubuntu:26.04:LTSlinux-aws7.0.0-1012.12UBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-aws-5.19no fix listedUBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-aws-6.14no fix listedUBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-aws-6.17no fix listedUBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-aws-6.2no fix listedUBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-aws-6.5no fix listedUBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-aws-6.86.8.0-1066.69~22.04.1UBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-aws-7.07.0.0-1012.12~24.04.1UBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-azure5.15.0-1123.132UBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-azure6.8.0-1070.78UBUNTU-CVE-2026-63867
Ubuntu:26.04:LTSlinux-azure7.0.0-1014.14UBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-azure-5.19no fix listedUBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-azure-6.11no fix listedUBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-azure-6.14no fix listedUBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-azure-6.17no fix listedUBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-azure-6.2no fix listedUBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-azure-6.5no fix listedUBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-azure-6.86.8.0-1070.78~22.04.1UBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-azure-7.07.0.0-1014.14~24.04.1UBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-azure-fde5.15.0-1122.131UBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-azure-fde6.8.0-1068.75UBUNTU-CVE-2026-63867
Ubuntu:26.04:LTSlinux-azure-fde7.0.0-1013.13UBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-azure-fde-5.19no fix listedUBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-azure-fde-6.14no fix listedUBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-azure-fde-6.17no fix listedUBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-azure-fde-6.2no fix listedUBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-azure-fde-6.86.8.0-1068.75~22.04.1UBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-azure-fde-7.07.0.0-1013.13~24.04.1UBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-azure-nvidiano fix listedUBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-azure-nvidia-6.14no fix listedUBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-gcp5.15.0-1118.128UBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-gcp6.8.0-1070.78UBUNTU-CVE-2026-63867
Ubuntu:26.04:LTSlinux-gcp7.0.0-1011.11UBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-gcp-5.19no fix listedUBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-gcp-6.11no fix listedUBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-gcp-6.14no fix listedUBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-gcp-6.17no fix listedUBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-gcp-6.2no fix listedUBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-gcp-6.5no fix listedUBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-gcp-6.86.8.0-1070.78~22.04.1UBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-gcp-7.07.0.0-1011.11~24.04.1UBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-gke5.15.0-1113.119UBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-gke6.8.0-1065.73UBUNTU-CVE-2026-63867
Ubuntu:26.04:LTSlinux-gke7.0.0-1006.7UBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-gkeop5.15.0-1100.108UBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-gkeop6.8.0-1051.55UBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-hwe-5.19no fix listedUBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-hwe-6.11no fix listedUBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-hwe-6.14no fix listedUBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-hwe-6.17no fix listedUBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-hwe-6.2no fix listedUBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-hwe-6.5no fix listedUBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-hwe-6.8no fix listedUBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-hwe-7.07.0.0-31.31~24.04.1UBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-ibm5.15.0-1111.115UBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-ibm6.8.0-1066.67UBUNTU-CVE-2026-63867
Ubuntu:26.04:LTSlinux-ibm7.0.0-1013.13UBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-ibm-6.86.8.0-1066.67~22.04.1UBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-intel-iot-realtimeno fix listedUBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-intel-iotg5.15.0-1112.118UBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-kvm5.15.0-1109.114UBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-lowlatency5.15.0-195.205UBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-lowlatency6.8.0-146.146.1UBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-lowlatency-hwe-5.19no fix listedUBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-lowlatency-hwe-6.11no fix listedUBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.2no fix listedUBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.5no fix listedUBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.86.8.0-146.146.1~22.04.1UBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-nvidia5.15.0-1112.113UBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-nvidia6.8.0-1064.67UBUNTU-CVE-2026-63867
Ubuntu:26.04:LTSlinux-nvidia7.0.0-1018.18UBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-nvidia-6.11no fix listedUBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-nvidia-6.17no fix listedUBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-nvidia-6.2no fix listedUBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-nvidia-6.5no fix listedUBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-nvidia-6.86.8.0-1064.67~22.04.1UBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-nvidia-7.07.0.0-1018.18~24.04.1UBUNTU-CVE-2026-63867
Ubuntu:26.04:LTSlinux-nvidia-bos7.0.0-2018.18UBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-nvidia-lowlatency6.8.0-1064.67.1UBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-nvidia-tegra5.15.0-1070.72UBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-nvidia-tegra6.8.0-1036.39UBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-nvidia-tegra-igx5.15.0-1059.59UBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-oem-5.17no fix listedUBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-oem-6.0no fix listedUBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-oem-6.1no fix listedUBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-oem-6.11no fix listedUBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-oem-6.14no fix listedUBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-oem-6.17no fix listedUBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-oem-6.5no fix listedUBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-oem-6.8no fix listedUBUNTU-CVE-2026-63867
Ubuntu:26.04:LTSlinux-oem-7.07.0.0-1013.13UBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-oracle5.15.0-1114.120UBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-oracle6.8.0-1063.66UBUNTU-CVE-2026-63867
Ubuntu:26.04:LTSlinux-oracle7.0.0-1011.11UBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-oracle-6.14no fix listedUBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-oracle-6.17no fix listedUBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-oracle-6.5no fix listedUBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-oracle-6.8no fix listedUBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-oracle-7.07.0.0-1011.11~24.04.1UBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-raspino fix listedUBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-raspino fix listedUBUNTU-CVE-2026-63867
Ubuntu:26.04:LTSlinux-raspi7.0.0-1019.19UBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-raspi-realtimeno fix listedUBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2026-63867
Ubuntu:26.04:LTSlinux-realtime7.0.0-31.31.1UBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2026-63867
Ubuntu:26.04:LTSlinux-riscv7.0.0-31.31.1UBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-riscv-5.19no fix listedUBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-riscv-6.14no fix listedUBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-riscv-6.17no fix listedUBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-riscv-6.5no fix listedUBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-riscv-6.86.8.0-146.146~22.04.1UBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-riscv-7.07.0.0-31.31.1~24.04.1UBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-starfive-5.19no fix listedUBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-starfive-6.2no fix listedUBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-starfive-6.5no fix listedUBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-vmware6.8.0-1008.8UBUNTU-CVE-2026-63867
Ubuntu:24.04:LTSlinux-xilinxno fix listedUBUNTU-CVE-2026-63867
Ubuntu:22.04:LTSlinux-xilinx-zynqmp5.15.0-1080.84UBUNTU-CVE-2026-63867

Affected products (as reported)

VendorProductVersions
Linux Linux fa3fe2b150316b294f2c662653501273ff25bba8 – before 301a33fd590c408a05c5df800e0cc1e6a8a2f8f8fa3fe2b150316b294f2c662653501273ff25bba8 – before 68364963e5baf03f16b4420292291f75c8f66497fa3fe2b150316b294f2c662653501273ff25bba8 – before 907ac6b1658e0277f979fcdfae2a753b495c1510fa3fe2b150316b294f2c662653501273ff25bba8 – before c4f4cf60797974873dbc8e100144682a6f2f861ffa3fe2b150316b294f2c662653501273ff25bba8 – before 3b8cbba7c0ed31189c89f90be247b8973ffa79effa3fe2b150316b294f2c662653501273ff25bba8 – before 8f4f0a157e8436a05bf8c3670b24dbc258911c43fa3fe2b150316b294f2c662653501273ff25bba8 – before 8ab24fdebc369c0dfb90f82c1650b1e66662bb45
Linux Linux 5.11

Weakness: CWE-362 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

References