Description
In the Linux kernel, the following vulnerability has been resolved:
mptcp: allow subflow rcv wnd to shrink
In MPTCP connection, the `window` field in the TCP header refers to the
MPTCP-level rcv_nxt and it's right edge should not move backward. Such
constraint is enforced at DSS option generation time.
At the same time, the TCP stack ensures independently that the TCP-level
rcv wnd right's edge does not move backward. That in turn causes artificial
inflating of the MPTCP rcv window when the incoming data is acked at the
TCP level and is OoO in the MPTCP sequence space (or lands in the backlog).
As a consequence, the incoming traffic can exceed the receiver rcvbuf size
even when the sender is not misbehaving.
Prevent such scenario forcibly allowing the TCP subflow to shrink the
TCP-level rcv wnd regardless of the current netns setting.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Linux | Linux | 5.19 | 6.1.176 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | linux | 7.0.13-1 | — |
| Debian 13 | linux | 6.12.94-1 | — |
| Debian 12 | linux | 6.1.176-1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Nvidia-BlueField 24.04 LTS | linux-bluefield | 6.8.0-1032.37 | — |
| Ubuntu 26.04 LTS | linux | 7.0.0-31.31 | USN-8726-1 |
| Ubuntu 26.04 LTS | linux-aws | 7.0.0-1012.12 | USN-8726-1 |
| Ubuntu 26.04 LTS | linux-azure | 7.0.0-1014.14 | USN-8726-4 |
| Ubuntu 26.04 LTS | linux-gcp +1 | 7.0.0-1011.11 | USN-8726-4, USN-8726-1 |
| Ubuntu 26.04 LTS | linux-gke | 7.0.0-1006.7 | USN-8726-1 |
| Ubuntu 26.04 LTS | linux-ibm +2 | 7.0.0-1013.13 | USN-8727-1, USN-8726-3 |
| Ubuntu 26.04 LTS | linux-nvidia | 7.0.0-1018.18 | USN-8760-2 |
| Ubuntu 26.04 LTS | linux-nvidia-bos | 7.0.0-2018.18 | USN-8800-1 |
| Ubuntu 26.04 LTS | linux-raspi | 7.0.0-1019.19 | USN-8726-2 |
| Ubuntu 26.04 LTS | linux-riscv +1 | 7.0.0-31.31.1 | USN-8726-1 |
| Ubuntu 25.10 | linux +8 | No fix yet | — |
| Ubuntu 24.04 LTS | linux | 6.8.0-146.146 | USN-8903-1 |
| Ubuntu 24.04 LTS | linux-aws | 6.8.0-1066.69 | USN-8903-1 |
| Ubuntu 24.04 LTS | linux-aws-7.0 | 7.0.0-1012.12~24.04.1 | USN-8726-1 |
| Ubuntu 24.04 LTS | linux-azure-7.0 | 7.0.0-1014.14~24.04.1 | USN-8728-2 |
| Ubuntu 24.04 LTS | linux-azure-fde | 6.8.0-1068.75 | USN-8904-1 |
| Ubuntu 24.04 LTS | linux-azure-fde-7.0 | 7.0.0-1013.13~24.04.1 | — |
| Ubuntu 24.04 LTS | linux-gcp +1 | 6.8.0-1070.78 | USN-8905-2, USN-8904-1 |
| Ubuntu 24.04 LTS | linux-gcp-7.0 +1 | 7.0.0-1011.11~24.04.1 | USN-8728-3, USN-8728-1 |
| Ubuntu 24.04 LTS | linux-gke | 6.8.0-1065.73 | USN-8903-2 |
| Ubuntu 24.04 LTS | linux-gkeop | 6.8.0-1051.55 | USN-8903-2 |
| Ubuntu 24.04 LTS | linux-hwe-7.0 | 7.0.0-31.31~24.04.1 | USN-8726-1 |
| Ubuntu 24.04 LTS | linux-ibm | 6.8.0-1066.67 | USN-8903-2 |
| Ubuntu 24.04 LTS | linux-lowlatency | 6.8.0-146.146.1 | USN-8903-2 |
| Ubuntu 24.04 LTS | linux-nvidia | 6.8.0-1064.67 | USN-8903-2 |
| Ubuntu 24.04 LTS | linux-nvidia-7.0 | 7.0.0-1018.18~24.04.1 | USN-8760-1 |
| Ubuntu 24.04 LTS | linux-nvidia-lowlatency | 6.8.0-1064.67.1 | USN-8903-2 |
| Ubuntu 24.04 LTS | linux-nvidia-tegra | 6.8.0-1035.38 | USN-8781-1 |
| Ubuntu 24.04 LTS | linux-oracle | 6.8.0-1063.66 | USN-8903-2 |
| Ubuntu 24.04 LTS | linux-raspi | 6.8.0-1068.72 | USN-9025-1 |
| Ubuntu 24.04 LTS | linux-riscv +29 | No fix yet | — |
| Ubuntu 24.04 LTS | linux-riscv-7.0 | 7.0.0-31.31.1~24.04.1 | — |
| Ubuntu 24.04 LTS | linux-vmware | 6.8.0-1008.8 | — |
| Ubuntu 22.04 LTS | linux-aws-6.8 | 6.8.0-1066.69~22.04.1 | USN-8903-1 |
| Ubuntu 22.04 LTS | linux-azure-fde-6.8 | 6.8.0-1068.75~22.04.1 | USN-8904-1 |
| Ubuntu 22.04 LTS | linux-gcp-6.8 +1 | 6.8.0-1070.78~22.04.1 | USN-8905-1, USN-8904-1 |
| Ubuntu 22.04 LTS | linux-hwe-6.8 | 6.8.0-149.149~22.04.1 | USN-9066-1 |
| Ubuntu 22.04 LTS | linux-ibm-6.8 | 6.8.0-1066.67~22.04.1 | USN-8906-1 |
| Ubuntu 22.04 LTS | linux-lowlatency-hwe-6.8 | 6.8.0-146.146.1~22.04.1 | USN-8903-2 |
| Ubuntu 22.04 LTS | linux-nvidia-6.8 | 6.8.0-1064.67~22.04.1 | USN-8903-2 |
| Ubuntu 22.04 LTS | linux-oracle-6.8 | 6.8.0-1067.71~22.04.1 | USN-9025-1 |
| Ubuntu 22.04 LTS | linux-riscv +32 | No fix yet | — |
| Ubuntu 22.04 LTS | linux-riscv-6.8 | 6.8.0-146.146~22.04.1 | — |
Show 6 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 20.04 LTS | linux-gke +28 | No fix yet | — |
| Ubuntu 18.04 LTS | linux-gcp +14 | No fix yet | — |
| Ubuntu 16.04 LTS | linux-hwe-edge | No fix yet | — |
| Ubuntu Pro Realtime 24.04 LTS | linux-raspi-realtime | 6.8.0-2056.58 | USN-9025-1 |
| Ubuntu Pro Realtime 24.04 LTS | linux-realtime | 6.8.1-1061.62 | USN-8903-1 |
| Ubuntu Pro Realtime 24.04 LTS | linux-realtime-6.14 +1 | No fix yet | — |
| Ubuntu Pro Realtime 22.04 LTS | linux-realtime-6.8 | 6.8.1-1061.62~22.04.1 | USN-8903-1 |
| Ubuntu Pro FIPS-updates 24.04 LTS | linux-aws-fips | 6.8.0-1066.69+fips1 | USN-8903-1 |
| Ubuntu Pro FIPS-updates 24.04 LTS | linux-azure-fips | 6.8.0-1069.77+fips1 | USN-8904-1 |
| Ubuntu Pro FIPS-updates 24.04 LTS | linux-fips | 6.8.0-146.146+fips1 | USN-8903-1 |
| Ubuntu Pro FIPS-updates 24.04 LTS | linux-gcp-fips | 6.8.0-1070.78+fips1 | USN-8905-1 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP7 | kernel-64kb +7 | 6.4.0-150700.53.78.1 | SUSE-SU-2026:3790-1 |
| SLES 15 SP7 | kernel-default-base | 6.4.0-150700.53.78.1.150700.17.43.2 | SUSE-SU-2026:3790-1 |
Show 7 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 16.0 | kernel-64kb +8 | 6.12.0-160000.37.1 | SUSE-SU-2026:23231-1, SUSE-SU-2026:23221-1 |
| SLES for SAP 16.0 | kernel-default-base | 6.12.0-160000.37.1.160000.2.19 | SUSE-SU-2026:23231-1, SUSE-SU-2026:23221-1 |
| SLES 16.0 | kernel-64kb +8 | 6.12.0-160000.37.1 | SUSE-SU-2026:23237-1, SUSE-SU-2026:23231-1, SUSE-SU-2026:23221-1 |
| SLES 16.0 | kernel-default-base | 6.12.0-160000.37.1.160000.2.19 | SUSE-SU-2026:23231-1, SUSE-SU-2026:23221-1 |
| SLE Micro 6.2 | kernel-default-base | 6.12.0-160000.37.1.160000.2.19 | SUSE-SU-2026:23068-1 |
| SLE Micro 6.2 | kernel-rt +5 | 6.12.0-160000.37.1 | SUSE-SU-2026:23068-1, SUSE-SU-2026:23066-1 |
| SLE Micro 6.1 | kernel-rt +4 | 6.4.0-51.1 | SUSE-SU-2026:23194-1, SUSE-SU-2026:23193-1 |
| SLE Micro 6.0 | kernel-rt +4 | 6.4.0-51.1 | SUSE-SU-2026:23244-1, SUSE-SU-2026:23241-1 |
| SLE Live Patching 15 SP7 | kernel-default | 6.4.0-150700.53.78.1 | SUSE-SU-2026:3790-1 |
| SLE Live Patching 15 SP7 | kernel-livepatch-SLE15-SP7-RT_Update_19 | 1-150700.1.5.1 | SUSE-SU-2026:3810-1 |
| SLE Live Patching 15 SP7 | kernel-livepatch-SLE15-SP7_Update_20 | 1-150700.15.3.2 | SUSE-SU-2026:3790-1 |
| SUSE Real Time Module 15 SP7 | kernel-rt +2 | 6.4.0-150700.7.72.1 | SUSE-SU-2026:3810-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Leap 16.0 | kernel-default-base | 6.12.0-160000.37.1.160000.2.19 | openSUSE-SU-2026:21555-1 |
| openSUSE Leap 16.0 | kernel-rt +11 | 6.12.0-160000.37.1 | openSUSE-SU-2026:21555-1 |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2023 | kernel-livepatch-6.18.36-69.134 +2 | 1:1.0-0.amzn2023 | ALAS2023-2026-1968, ALAS2023-2026-1925, ALAS2023-2026-1924 |
| Amazon Linux 2023 | perf +11 | 1:6.1.176-220.358.amzn2023 | ALAS2023-2026-1924 |
| Amazon Linux 2023 | perf6.12 +11 | 1:6.12.94-123.174.amzn2023 | ALAS2023-2026-1968 |
| Amazon Linux 2023 | perf6.18 +12 | 1:6.18.36-69.134.amzn2023 | ALAS2023-2026-1925 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | kernel | 6.6.143.1-1 | — |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 9 | kernel-uek +34 | 6.12.0-206.104.3.3.el10uek | ELSA-2026-500248 |
Advisories 40
- USN-9066-1 linux-hwe-6.8 vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
- WID-SEC-2026-2077 Linux Kernel: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 12, 2026
- USN-9025-1 linux-oracle-6.8, linux-raspi, linux-raspi-realtime vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
- USN-8726-1 linux, linux-aws, linux-aws-7.0, linux-gcp, linux-gke, linux-hwe-7.0, linux-realtime vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
- USN-8726-4 linux-azure, linux-oracle vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
- USN-8728-1 linux-gcp-7.0 vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
- USN-8728-2 linux-azure-7.0 vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
- USN-8760-1 linux-nvidia-7.0 vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
- USN-8800-1 linux-nvidia-bos vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
- USN-8728-3 linux-oracle-7.0 vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
- USN-8760-2 linux-nvidia vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
- USN-8726-3 linux-ibm vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
- USN-8727-1 linux-oem-7.0 vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
- USN-8726-2 linux-raspi vulnerabilities Ubuntu Security Notices (USN) · Nov 12, 2026
- USN-8903-2 linux-gke, linux-gkeop, linux-ibm, linux-lowlatency, linux-lowlatency-hwe-6.8, linux-nvidia, linux-nvidia-6.8, linux-nvidia-lowlatency, linux-oracle vulnerabilities Ubuntu Security Notices (USN) · Nov 9, 2026
- USN-8903-1 linux, linux-aws, linux-aws-6.8, linux-aws-fips, linux-fips, linux-realtime, linux-realtime-6.8 vulnerabilities Ubuntu Security Notices (USN) · Nov 9, 2026
- USN-8904-1 linux-azure, linux-azure-6.8, linux-azure-fde, linux-azure-fde-6.8, linux-azure-fips vulnerabilities Ubuntu Security Notices (USN) · Nov 9, 2026
- USN-8905-2 linux-gcp vulnerabilities Ubuntu Security Notices (USN) · Nov 9, 2026
- USN-8905-1 linux-gcp-6.8, linux-gcp-fips vulnerabilities Ubuntu Security Notices (USN) · Nov 9, 2026
- USN-8906-1 linux-ibm-6.8 vulnerabilities Ubuntu Security Notices (USN) · Nov 9, 2026
- USN-8781-1 linux-nvidia-tegra vulnerabilities Ubuntu Security Notices (USN) · Nov 9, 2026
- ICSA-26-295-16 Siemens SIMATIC S7-1500 TM MFP CISA ICS & IT advisories · Oct 22, 2026
- WID-SEC-2026-3891 Siemens SIMATIC S7: Mehrere Schwachstelle BSI CERT-Bund (WID) · Oct 18, 2026
- SSA-784472 SSA-784472: Vulnerabilities in the additional GNU/Linux subsystem of the SIMATIC S7-1500 TM MFP V1.1.1 Siemens ProductCERT · Oct 13, 2026
- ELSA-2026-500248 Important: Unbreakable Enterprise kernel security update (Oracle Linux 9) Oracle Linux Security Advisories (ELSA) · Sep 4, 2026
- SUSE-SU-2026:3810-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Aug 31, 2026
- SUSE-SU-2026:23244-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Aug 27, 2026
- SUSE-SU-2026:23231-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Aug 27, 2026
- SUSE-SU-2026:23237-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Aug 27, 2026
- SUSE-SU-2026:23241-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Aug 27, 2026
- SUSE-SU-2026:23221-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Aug 27, 2026
- SUSE-SU-2026:3790-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Aug 27, 2026
- SUSE-SU-2026:23194-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Aug 26, 2026
- SUSE-SU-2026:23193-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Aug 26, 2026
- SUSE-SU-2026:23066-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Aug 15, 2026
- SUSE-SU-2026:23068-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Aug 15, 2026
- openSUSE-SU-2026:21555-1 Security update for the Linux Kernel SUSE / openSUSE Security Updates · Aug 12, 2026
- ALAS2023-2026-1924 Important: kernel security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Aug 12, 2026
- ALAS2023-2026-1968 Important: kernel6.12 security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Aug 12, 2026
- ALAS2023-2026-1925 Important: kernel6.18 security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Jul 29, 2026
References
- https://git.kernel.org/stable/c/bf364b0f10b27679140699821f88af7f01e2a6e3
- https://git.kernel.org/stable/c/b1fd13074f22105deec45aa02283e322733e0c2d
- https://git.kernel.org/stable/c/aa3861f40ac32706d9e97bfac76984613e278788
- https://git.kernel.org/stable/c/653245266913f03fcf21cbca68eed5c197a33e52
- https://git.kernel.org/stable/c/c297a4e65c50a2b807d9309b22615080faffa8f3
- https://git.kernel.org/stable/c/da23be77e1292cd611e736c3aa17da633d7ddce7