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8.1

CVE-2026-68118: Linux kernel TCP can drop connections improperly

CVE-2026-68118 · published 2 months ago
Summary

A bug in the Linux kernel’s TCP code could allow certain reset packets to close a network connection without the usual safety checks. This may let an attacker disrupt communications on systems running Debian or Ubuntu variants of Linux. Updating the operating system to the latest kernel release from your vendor resolves the issue.

What to do
  • Update debian linux to version 7.1.6-1.
  • Update debian linux to version 6.12.105-1.
  • Update debian linux-6.12 to version 6.12.107-1~deb12u1.
  • Update bellsoft linux-lts to version 6.12.111-r0.
  • Update bellsoft linux-lts to version 6.18.43-r0.
  • Update linux kernel to version 7.1.6.
  • Update canonical linux-nvidia-tegra to version 6.8.0-1036.39.
  • Update canonical linux to version 7.0.0-38.38.
  • Update canonical linux-aws to version 7.0.0-1014.14.
  • Update canonical linux-azure to version 7.0.0-1017.17.
  • Update canonical linux-azure-fde to version 7.0.0-1016.16.
  • Update canonical linux-gcp to version 7.0.0-1014.14.
  • Update canonical linux-gke to version 7.0.0-1008.9.
  • Update canonical linux-ibm to version 7.0.0-1015.15.
  • Update canonical linux-oem-7.0 to version 7.0.0-1015.15.
  • Update canonical linux-oracle to version 7.0.0-1013.13.
  • Update canonical linux-realtime to version 7.0.0-38.38.1.
  • Update canonical linux-aws-7.0 to version 7.0.0-1014.14~24.04.1.
  • Update canonical linux-azure-7.0 to version 7.0.0-1017.17~24.04.1.
  • Update canonical linux-azure-fde-7.0 to version 7.0.0-1016.16~24.04.1.
  • Update canonical linux-gcp-7.0 to version 7.0.0-1014.14~24.04.1.
  • Update canonical linux-hwe-7.0 to version 7.0.0-38.38~24.04.4.
  • Update canonical linux-oracle-7.0 to version 7.0.0-1013.13~24.04.1.
  • Update canonical linux-riscv-7.0 to version 7.0.0-38.38.1~24.04.1.
  • Update canonical linux-riscv to version 7.0.0-38.38.1.
  • Update bellsoft linux-lts to version 6.1.191-r0.
Affected software
Ecosystem VendorProductAffected versions
Debian:11 debian linux All versions
Debian:12 debian linux All versions
Debian:13 debian linux < 6.12.105-1
Fix: upgrade to 6.12.105-1
Debian:14 debian linux < 7.1.6-1
Fix: upgrade to 7.1.6-1
Ubuntu:Pro:14.04:LTS canonical linux All versions
Ubuntu:Pro:14.04:LTS canonical linux-aws All versions
Ubuntu:Pro:14.04:LTS canonical linux-azure All versions
Ubuntu:Pro:14.04:LTS canonical linux-lts-xenial All versions
Ubuntu:Pro:16.04:LTS canonical linux-aws-hwe All versions
Ubuntu:Pro:16.04:LTS canonical linux-gcp All versions
Ubuntu:Pro:16.04:LTS canonical linux-hwe All versions
Ubuntu:16.04:LTS canonical linux-hwe-edge All versions
Ubuntu:Pro:16.04:LTS canonical linux-kvm All versions
Ubuntu:Pro:16.04:LTS canonical linux-oracle All versions
Ubuntu:Pro:FIPS:16.04:LTS canonical linux-fips All versions
Ubuntu:18.04:LTS canonical linux-aws-5.0 All versions
Ubuntu:18.04:LTS canonical linux-aws-5.3 All versions
Ubuntu:Pro:18.04:LTS canonical linux-aws-5.4 All versions
Ubuntu:Pro:18.04:LTS canonical linux-azure-4.15 All versions
Ubuntu:18.04:LTS canonical linux-azure-5.3 All versions
Ubuntu:Pro:18.04:LTS canonical linux-azure-5.4 All versions
Ubuntu:18.04:LTS canonical linux-azure-edge All versions
Ubuntu:Pro:18.04:LTS canonical linux-gcp-4.15 All versions
Ubuntu:18.04:LTS canonical linux-gcp-5.3 All versions
Ubuntu:Pro:18.04:LTS canonical linux-gcp-5.4 All versions
Ubuntu:18.04:LTS canonical linux-gke-4.15 All versions
Ubuntu:18.04:LTS canonical linux-gke-5.4 All versions
Ubuntu:18.04:LTS canonical linux-gkeop-5.4 All versions
Ubuntu:Pro:18.04:LTS canonical linux-hwe-5.4 All versions
Ubuntu:Pro:18.04:LTS canonical linux-ibm-5.4 All versions
Ubuntu:18.04:LTS canonical linux-oem All versions
Ubuntu:18.04:LTS canonical linux-oracle-5.0 All versions
Ubuntu:18.04:LTS canonical linux-oracle-5.3 All versions
Ubuntu:Pro:18.04:LTS canonical linux-oracle-5.4 All versions
Ubuntu:Pro:18.04:LTS canonical linux-raspi-5.4 All versions
Ubuntu:Pro:FIPS-updates:18.04:LTS canonical linux-aws-fips All versions
Ubuntu:Pro:FIPS-updates:18.04:LTS canonical linux-azure-fips All versions
Ubuntu:Pro:FIPS-updates:18.04:LTS canonical linux-gcp-fips All versions
Ubuntu:20.04:LTS canonical linux-aws-5.11 All versions
Ubuntu:20.04:LTS canonical linux-aws-5.13 All versions
Ubuntu:Pro:20.04:LTS canonical linux-aws-5.15 All versions
Ubuntu:20.04:LTS canonical linux-aws-5.8 All versions
Ubuntu:20.04:LTS canonical linux-azure-5.11 All versions
Ubuntu:20.04:LTS canonical linux-azure-5.13 All versions
Ubuntu:Pro:20.04:LTS canonical linux-azure-5.15 All versions
Ubuntu:20.04:LTS canonical linux-azure-5.8 All versions
Ubuntu:20.04:LTS canonical linux-azure-fde All versions
Ubuntu:Pro:20.04:LTS canonical linux-azure-fde-5.15 All versions
Ubuntu:Pro:20.04:LTS canonical linux-bluefield All versions
Ubuntu:20.04:LTS canonical linux-gcp-5.11 All versions
Showing 50 of 190. Show the rest
Ecosystem VendorProductAffected versions
Ubuntu:20.04:LTS canonical linux-gcp-5.13 All versions
Ubuntu:Pro:20.04:LTS canonical linux-gcp-5.15 All versions
Ubuntu:20.04:LTS canonical linux-gcp-5.8 All versions
Ubuntu:20.04:LTS canonical linux-gke All versions
Ubuntu:20.04:LTS canonical linux-gke-5.15 All versions
Ubuntu:20.04:LTS canonical linux-gkeop All versions
Ubuntu:20.04:LTS canonical linux-gkeop-5.15 All versions
Ubuntu:20.04:LTS canonical linux-hwe-5.11 All versions
Ubuntu:20.04:LTS canonical linux-hwe-5.13 All versions
Ubuntu:Pro:20.04:LTS canonical linux-hwe-5.15 All versions
Ubuntu:20.04:LTS canonical linux-hwe-5.8 All versions
Ubuntu:Pro:20.04:LTS canonical linux-ibm All versions
Ubuntu:Pro:20.04:LTS canonical linux-ibm-5.15 All versions
Ubuntu:20.04:LTS canonical linux-intel-5.13 All versions
Ubuntu:Pro:20.04:LTS canonical linux-intel-iotg-5.15 All versions
Ubuntu:Pro:20.04:LTS canonical linux-iot All versions
Ubuntu:Pro:20.04:LTS canonical linux-lowlatency-hwe-5.15 All versions
Ubuntu:Pro:20.04:LTS canonical linux-nvidia-tegra-5.15 All versions
Ubuntu:20.04:LTS canonical linux-oem-5.10 All versions
Ubuntu:20.04:LTS canonical linux-oem-5.13 All versions
Ubuntu:20.04:LTS canonical linux-oem-5.14 All versions
Ubuntu:20.04:LTS canonical linux-oem-5.6 All versions
Ubuntu:20.04:LTS canonical linux-oracle-5.11 All versions
Ubuntu:20.04:LTS canonical linux-oracle-5.13 All versions
Ubuntu:Pro:20.04:LTS canonical linux-oracle-5.15 All versions
Ubuntu:20.04:LTS canonical linux-oracle-5.8 All versions
Ubuntu:Pro:20.04:LTS canonical linux-raspi All versions
Ubuntu:20.04:LTS canonical linux-raspi2 All versions
Ubuntu:20.04:LTS canonical linux-riscv All versions
Ubuntu:20.04:LTS canonical linux-riscv-5.11 All versions
Ubuntu:Pro:20.04:LTS canonical linux-riscv-5.15 All versions
Ubuntu:20.04:LTS canonical linux-riscv-5.8 All versions
Ubuntu:Pro:20.04:LTS canonical linux-xilinx-zynqmp All versions
Ubuntu:22.04:LTS canonical linux-allwinner-5.19 All versions
Ubuntu:22.04:LTS canonical linux-aws-5.19 All versions
Ubuntu:22.04:LTS canonical linux-aws-6.2 All versions
Ubuntu:22.04:LTS canonical linux-aws-6.5 All versions
Ubuntu:22.04:LTS canonical linux-aws-6.8 All versions
Ubuntu:22.04:LTS canonical linux-azure-5.19 All versions
Ubuntu:22.04:LTS canonical linux-azure-6.2 All versions
Ubuntu:22.04:LTS canonical linux-azure-6.5 All versions
Ubuntu:22.04:LTS canonical linux-azure-6.8 All versions
Ubuntu:22.04:LTS canonical linux-azure-fde-5.19 All versions
Ubuntu:22.04:LTS canonical linux-azure-fde-6.2 All versions
Ubuntu:22.04:LTS canonical linux-azure-fde-6.8 All versions
Ubuntu:22.04:LTS canonical linux-gcp-5.19 All versions
Ubuntu:22.04:LTS canonical linux-gcp-6.2 All versions
Ubuntu:22.04:LTS canonical linux-gcp-6.5 All versions
Ubuntu:22.04:LTS canonical linux-gcp-6.8 All versions
Ubuntu:22.04:LTS canonical linux-hwe-5.19 All versions
Ubuntu:22.04:LTS canonical linux-hwe-6.2 All versions
Ubuntu:22.04:LTS canonical linux-hwe-6.5 All versions
Ubuntu:22.04:LTS canonical linux-hwe-6.8 All versions
Ubuntu:22.04:LTS canonical linux-ibm-6.8 All versions
Ubuntu:22.04:LTS canonical linux-intel-iot-realtime All versions
Ubuntu:22.04:LTS canonical linux-intel-iotg All versions
Ubuntu:22.04:LTS canonical linux-lowlatency All versions
Ubuntu:22.04:LTS canonical linux-lowlatency-hwe-5.19 All versions
Ubuntu:22.04:LTS canonical linux-lowlatency-hwe-6.2 All versions
Ubuntu:22.04:LTS canonical linux-lowlatency-hwe-6.5 All versions
Ubuntu:22.04:LTS canonical linux-lowlatency-hwe-6.8 All versions
Ubuntu:22.04:LTS canonical linux-nvidia All versions
Ubuntu:22.04:LTS canonical linux-nvidia-6.2 All versions
Ubuntu:22.04:LTS canonical linux-nvidia-6.5 All versions
Ubuntu:22.04:LTS canonical linux-nvidia-6.8 All versions
Ubuntu:22.04:LTS canonical linux-nvidia-tegra All versions
Ubuntu:22.04:LTS canonical linux-nvidia-tegra-igx All versions
Ubuntu:22.04:LTS canonical linux-oem-5.17 All versions
Ubuntu:22.04:LTS canonical linux-oem-6.0 All versions
Ubuntu:22.04:LTS canonical linux-oem-6.1 All versions
Ubuntu:22.04:LTS canonical linux-oem-6.5 All versions
Ubuntu:22.04:LTS canonical linux-oracle-6.5 All versions
Ubuntu:22.04:LTS canonical linux-oracle-6.8 All versions
Ubuntu:22.04:LTS canonical linux-realtime All versions
Ubuntu:22.04:LTS canonical linux-riscv-5.19 All versions
Ubuntu:22.04:LTS canonical linux-riscv-6.5 All versions
Ubuntu:22.04:LTS canonical linux-riscv-6.8 All versions
Ubuntu:22.04:LTS canonical linux-starfive-5.19 All versions
Ubuntu:22.04:LTS canonical linux-starfive-6.2 All versions
Ubuntu:22.04:LTS canonical linux-starfive-6.5 All versions
Ubuntu:Pro:Realtime:22.04:LTS canonical linux-realtime-6.8 All versions
Ubuntu:24.04:LTS canonical linux-aws-6.14 All versions
Ubuntu:24.04:LTS canonical linux-aws-6.17 All versions
Ubuntu:24.04:LTS canonical linux-aws-7.0 < 7.0.0-1014.14~24.04.1
Fix: upgrade to 7.0.0-1014.14~24.04.1
Ubuntu:24.04:LTS canonical linux-azure-6.11 All versions
Ubuntu:24.04:LTS canonical linux-azure-6.14 All versions
Ubuntu:24.04:LTS canonical linux-azure-6.17 All versions
Ubuntu:24.04:LTS canonical linux-azure-7.0 < 7.0.0-1017.17~24.04.1
Fix: upgrade to 7.0.0-1017.17~24.04.1
Ubuntu:24.04:LTS canonical linux-azure-fde-6.14 All versions
Ubuntu:24.04:LTS canonical linux-azure-fde-6.17 All versions
Ubuntu:24.04:LTS canonical linux-azure-fde-7.0 < 7.0.0-1016.16~24.04.1
Fix: upgrade to 7.0.0-1016.16~24.04.1
Ubuntu:24.04:LTS canonical linux-azure-nvidia All versions
Ubuntu:24.04:LTS canonical linux-azure-nvidia-6.14 All versions
Ubuntu:24.04:LTS canonical linux-gcp-6.11 All versions
Ubuntu:24.04:LTS canonical linux-gcp-6.14 All versions
Ubuntu:24.04:LTS canonical linux-gcp-6.17 All versions
Ubuntu:24.04:LTS canonical linux-gcp-7.0 < 7.0.0-1014.14~24.04.1
Fix: upgrade to 7.0.0-1014.14~24.04.1
Ubuntu:24.04:LTS canonical linux-hwe-6.11 All versions
Ubuntu:24.04:LTS canonical linux-hwe-6.14 All versions
Ubuntu:24.04:LTS canonical linux-hwe-6.17 All versions
Ubuntu:24.04:LTS canonical linux-hwe-7.0 < 7.0.0-38.38~24.04.4
Fix: upgrade to 7.0.0-38.38~24.04.4
Ubuntu:24.04:LTS canonical linux-lowlatency-hwe-6.11 All versions
Ubuntu:24.04:LTS canonical linux-nvidia-6.11 All versions
Ubuntu:24.04:LTS canonical linux-nvidia-6.17 All versions
Ubuntu:24.04:LTS canonical linux-nvidia-7.0 All versions
Ubuntu:24.04:LTS canonical linux-nvidia-lowlatency All versions
Ubuntu:24.04:LTS canonical linux-oem-6.11 All versions
Ubuntu:24.04:LTS canonical linux-oem-6.14 All versions
Ubuntu:24.04:LTS canonical linux-oem-6.17 All versions
Ubuntu:24.04:LTS canonical linux-oem-6.8 All versions
Ubuntu:24.04:LTS canonical linux-oracle-6.14 All versions
Ubuntu:24.04:LTS canonical linux-oracle-6.17 All versions
Ubuntu:24.04:LTS canonical linux-oracle-7.0 < 7.0.0-1013.13~24.04.1
Fix: upgrade to 7.0.0-1013.13~24.04.1
Ubuntu:24.04:LTS canonical linux-raspi-realtime All versions
Ubuntu:24.04:LTS canonical linux-riscv-6.14 All versions
Ubuntu:24.04:LTS canonical linux-riscv-6.17 All versions
Ubuntu:24.04:LTS canonical linux-riscv-7.0 < 7.0.0-38.38.1~24.04.1
Fix: upgrade to 7.0.0-38.38.1~24.04.1
Ubuntu:24.04:LTS canonical linux-xilinx All versions
Ubuntu:Pro:Realtime:24.04:LTS canonical linux-realtime-6.14 All versions
Ubuntu:Pro:Realtime:24.04:LTS canonical linux-realtime-6.17 All versions
Ubuntu:26.04:LTS canonical linux-nvidia-bos All versions
Ubuntu:26.04:LTS canonical linux-oem-7.0 < 7.0.0-1015.15
Fix: upgrade to 7.0.0-1015.15
– linux linux < 234f9ffbd9b2c1b24ec67200ea3cff07401bec48
3.6
< 8b0a3a094f4cae2fb92e4d08d4eef7246a9d9c49
< c5dc463cc60eb26079b19607c9dbda76491dad05
Debian:12 debian linux-6.12 < 6.12.107-1~deb12u1
Fix: upgrade to 6.12.107-1~deb12u1
Alpaquita:23 bellsoft linux-lts >= 6.1.177-r0
>= 6.1.189-r0, < 6.1.191-r0
Fix: upgrade to 6.1.191-r0
Alpaquita:25 bellsoft linux-lts >= 6.12.103-r0, < 6.12.111-r0
Fix: upgrade to 6.12.111-r0
Alpaquita:stream bellsoft linux-lts >= 6.18.38-r0, < 6.18.43-r0
Fix: upgrade to 6.18.43-r0
Linux linux kernel >= 6.19.0, < 7.1.6
Fix: upgrade to 7.1.6
Ubuntu:24.04:LTS canonical linux-nvidia-tegra < 6.8.0-1036.39
Fix: upgrade to 6.8.0-1036.39
Ubuntu:26.04:LTS canonical linux < 7.0.0-38.38
Fix: upgrade to 7.0.0-38.38
Ubuntu:26.04:LTS canonical linux-aws < 7.0.0-1014.14
Fix: upgrade to 7.0.0-1014.14
Ubuntu:26.04:LTS canonical linux-azure < 7.0.0-1017.17
Fix: upgrade to 7.0.0-1017.17
Ubuntu:26.04:LTS canonical linux-azure-fde < 7.0.0-1016.16
Fix: upgrade to 7.0.0-1016.16
Ubuntu:26.04:LTS canonical linux-gcp < 7.0.0-1014.14
Fix: upgrade to 7.0.0-1014.14
Ubuntu:26.04:LTS canonical linux-gke < 7.0.0-1008.9
Fix: upgrade to 7.0.0-1008.9
Ubuntu:26.04:LTS canonical linux-ibm < 7.0.0-1015.15
Fix: upgrade to 7.0.0-1015.15
Ubuntu:26.04:LTS canonical linux-oracle < 7.0.0-1013.13
Fix: upgrade to 7.0.0-1013.13
Ubuntu:26.04:LTS canonical linux-realtime < 7.0.0-38.38.1
Fix: upgrade to 7.0.0-38.38.1
Ubuntu:24.04:LTS canonical linux-vmware All versions
Ubuntu:26.04:LTS canonical linux-riscv < 7.0.0-38.38.1
Fix: upgrade to 7.0.0-38.38.1
Original advisory text
BELL-CVE-2026-68118
In the Linux kernel, the following vulnerability has been resolved:

tcp: challenge ACK for non-exact RST in SYN-RECEIVED

The SYN-RECEIVED request-socket path in tcp_check_req() accepts an
in-window RST without requiring SEG.SEQ to exactly match RCV.NXT. A
non-exact RST therefore removes the request instead of eliciting a
challenge ACK.

RFC 9293 section 3.10.7.4 applies the RFC 5961 reset check in
SYN-RECEIVED: an exact RST resets the connection, while a non-exact
in-window RST must trigger a challenge ACK and be dropped.

Apply that check before the ACK-field validation, following the RFC
sequence-number, RST, then ACK processing order. Factor the per-netns
challenge ACK quota out of tcp_send_challenge_ack() so request sockets
can share it. Use the request socket's send_ack() callback and its own
out-of-window ACK timestamp to send and rate-limit the response.
Fix within
Internet-facing 14 days
Internal 60 days
  • Not known to be exploited
  • Can be exploited automatically
  • Gives an attacker partial control
Severity
8.1 High
Exploitation
<1% chance of attack within 30 days
Type
CWE-20Improper Input Validation
Timeline
Published12 Aug 2026
Updated4 Nov 2026
First seen10 Aug 2026
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