Integer underflow in Linux kernel - CVE-2026-98550

Vulnerability identifier: #VU156852

CSH Severity: Low

CVSS v4: 5.3 [CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-98550

CWE-ID: CWE-191

Exploitation vector: Adjecent network

Exploit availability: No public exploit available

The vulnerability allows a remote attacker on the local network to cause a denial of service by blocking future TIPC group broadcasts on an affected socket.

The vulnerability exists due to integer underflow caused by incomplete acknowledgment validation in tipc_group_proto_rcv() when processing TIPC group acknowledgment messages. A remote attacker on the local network can send unexpected or incorrectly sequenced GRP_ACK_MSG messages to decrement the broadcast acknowledgment counter improperly, potentially wrapping it to 65535 and causing persistent congestion on the affected socket.

Linux kernel
Ubuntu
linux-nvidia-tegra (Ubuntu package)
linux-nvidia-tegra-igx (Ubuntu package)
linux-nvidia-tegra-5.15 (Ubuntu package)
linux (Ubuntu package)
linux-gcp (Ubuntu package)
linux-oracle (Ubuntu package)
linux-aws (Ubuntu package)
linux-ibm (Ubuntu package)
linux-hwe-7.0 (Ubuntu package)
linux-oem-7.0 (Ubuntu package)

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
linux-nvidia-tegra (Ubuntu package) - update to 5.15.0-1070.72
linux-nvidia-tegra-igx (Ubuntu package) - update to 5.15.0-1059.59
linux-nvidia-tegra-5.15 (Ubuntu package) - update to 5.15.0-1070.72~20.04.1
linux (Ubuntu package) - update to 7.0.0-42.42
linux-gcp (Ubuntu package) - update to 7.0.0-1016.18
linux-oracle (Ubuntu package) - update to 7.0.0-1015.16
linux-aws (Ubuntu package) - update to 7.0.0-1016.17
linux-ibm (Ubuntu package) - update to 7.0.0-1017.17
linux-hwe-7.0 (Ubuntu package) - update to 7.0.0-42.42~24.04.1
linux-oem-7.0 (Ubuntu package) - update to 7.0.0-1017.17

• https://git.kernel.org/stable/c/12cc3a1eac5a2a06b67a7b85f0f48ff241a94d1b
• https://git.kernel.org/stable/c/478fb08d0c2a53002a721d22b8d6681ec971d90f
• https://git.kernel.org/stable/c/507a27435b2bb1f22e3a3674f6a6553eb815021b
• https://git.kernel.org/stable/c/80a9ccfc24d3776ef6753a57315e726475fac7d7
• https://git.kernel.org/stable/c/99cc2a62e07a44a22254d7beca9ef1f8ad886d0d
• https://git.kernel.org/stable/c/9b94a90651e1fa573c6ac6a5a6b269d5874df2c0
• https://git.kernel.org/stable/c/b0e517961f09b9f60d338d1ea4e17aacdbf206f0
• https://git.kernel.org/stable/c/edc6593c442278fceff0120e8cc58bc592168c35

• Integer underflow in Linux kernel tipc
• Ubuntu update for linux-oem-7.0
• Ubuntu update for linux, linux-aws, linux-gcp and more
• Ubuntu update for linux-nvidia-tegra, linux-nvidia-tegra-5.15, linux-nvidia-tegra-igx
• Ubuntu update for linux, linux-aws, linux-aws-5.15 and more