Unexpected Sign Extension in Linux kernel - CVE-2026-98590

Vulnerability identifier: #VU156893

CSH Severity: Low

CVSS v4: 8.5 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-98590

CWE-ID: CWE-194

Exploitation vector: Local access

Exploit availability: No public exploit available

The vulnerability allows a local user to bypass BPF verifier assumptions about the range of runtime register values.

The vulnerability exists due to unexpected sign extension and incorrect destination-size accounting in bpf_sock context access code generation when processing access to the rx_queue_mapping field. A local user can execute a specially crafted BPF program that right-shifts the sign-extended value to produce a runtime value outside the bounds assumed by the verifier.

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/4a41d064facc3330e176ecbbf5b0026ed18a5c69
• https://git.kernel.org/stable/c/4a4852376e3a2727ea40e61143d6d7c22bb6dfad
• https://git.kernel.org/stable/c/70288599d1754e157df8326239316dbdf08ea33c
• https://git.kernel.org/stable/c/84ebb991ae985149079ae9ab51b7e3ba25a9ff53
• https://git.kernel.org/stable/c/b3f37afc7fd7c52bc2114310aff1eb24c7cd4d73
• https://git.kernel.org/stable/c/d95dd5a6c6cd08d5ae466d3aed27b3cf59155a6c
• https://git.kernel.org/stable/c/e3ddcf4aeb342d4de2e5761c7042270d454752de
• https://git.kernel.org/stable/c/ea4dc96c902ccfa49dd3e4f23c443dab4a74b018

• Unexpected Sign Extension in Linux kernel core
• 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