Improper access control in Linux kernel - CVE-2026-63830
Published: July 20, 2026
Vulnerability identifier: #VU138821
CSH Severity: Low
CVSS v4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-63830
CWE-ID: CWE-284
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a local user to modify the page cache contents.
The vulnerability exists due to improper access control in the sk_msg scatter-gather handling logic when processing SK_MSG transformations and BPF message helpers. A local user can trigger scatterlist entry transfers, shifts, splits, or copies that desynchronize sg.copy state to modify the page cache contents.
Exploitation requires the ability to reach a later SK_MSG verdict that exposes sg_virt(sge) as writable BPF ctx->data.
Affected software
Linux kernel
How to mitigate CVE-2026-63830
Install security update from vendor's repository.
Linux kernel - update to 7.0 rc3
External References
- https://git.kernel.org/stable/c/0eb4c16c4adb262763bda870a8ed38a1a9dec7ec
- https://git.kernel.org/stable/c/1acdd14c0990dd1cd4b6534f00366d2e6dfce05f
- https://git.kernel.org/stable/c/21ed9540a8e1906dfcbc1bb82ba9b4de4fa4bd6d
- https://git.kernel.org/stable/c/406e8a651a7b854c41fecd5117bb282b3a6c2c6b
- https://git.kernel.org/stable/c/9bb86d8184b37503816150c4a6ad3c17dfdbe827
- https://git.kernel.org/stable/c/d22cc92bc41290e5783a72375e0843d9435f6001