Out-of-bounds write in Linux kernel - CVE-2026-63794
Published: July 21, 2026
Vulnerability identifier: #VU138865
CSH Severity: Low
CVSS v4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-63794
CWE-ID: CWE-787
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a local user to cause memory corruption.
The vulnerability exists due to an out-of-bounds write in sev_dbg_crypt() when processing crafted KVM SEV debug encryption requests. A local user can send a crafted ioctl request with page offsets that cause the transfer length to exceed the destination page boundary to cause memory corruption.
The issue affects the encrypt path and can overflow a single-page intermediate buffer by up to 15 bytes when the destination offset is greater than the source offset.
Affected software
Linux kernel
How to mitigate CVE-2026-63794
Install security update from vendor's repository.
Linux kernel - update to 7.0 rc3
External References
- https://git.kernel.org/stable/c/2753a097d1fe24c4351c608048612c74108aa89f
- https://git.kernel.org/stable/c/64f2449841ffc7d203183aa4c748c9c77951ecc5
- https://git.kernel.org/stable/c/720949ed666f34ff28ffdfe1471a5861d1e41fdf
- https://git.kernel.org/stable/c/78ee2d50185a037b3d2452a97f3dad69c3f7f389
- https://git.kernel.org/stable/c/889c2a9c59897ca912bf39df5bb92555a0a13df4
- https://git.kernel.org/stable/c/9349b50f4b11f135fe73b56cb2c2c872d8bc71d7
- https://git.kernel.org/stable/c/e1a0fe288dee07b7da25a71e007c1ecd1080315b
- https://git.kernel.org/stable/c/f701ae476cb92a3a3d8844bb39bb63b4512684c8