Off-by-one in Linux kernel - CVE-2026-46066

Vulnerability identifier: #VU132423

CSH Severity: Low

CVSS v4: 5.7 [CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-46066

CWE-ID: CWE-193

Exploitation vector: Local access

Exploit availability: No public exploit available

The vulnerability allows a local user to cause a denial of service.

The vulnerability exists due to an off-by-one error in ceph_process_folio_batch() when handling encrypted CephFS writeback after bounce buffer allocation failure. A local user can write to fscrypt-enabled CephFS files under memory pressure to trigger a kernel panic and cause a denial of service.

The issue is triggered when processing a 4KiB-written/4KiB-skipped pattern and the failed folio is not contiguous with the last folio already added to the batch.

Linux kernel
Debian Linux
Ubuntu
linux (Ubuntu package)
linux-realtime (Ubuntu package)
linux-oracle (Ubuntu package)
linux-aws (Ubuntu package)
linux-gcp (Ubuntu package)
linux-raspi (Ubuntu package)
linux-azure (Ubuntu package)
linux-nvidia (Ubuntu package)
linux-ibm (Ubuntu package)
linux-azure-fde (Ubuntu package)
linux (Debian package)

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
linux (Ubuntu package) - update to 7.0.0-27.27
linux-realtime (Ubuntu package) - update to 7.0.0-27.27.1
linux-oracle (Ubuntu package) - update to 7.0.0-1007.7
linux-aws (Ubuntu package) - update to 7.0.0-1008.8
linux-gcp (Ubuntu package) - update to 7.0.0-1007.7
linux-raspi (Ubuntu package) - update to 7.0.0-1014.14
linux-azure (Ubuntu package) - update to 7.0.0-1010.10
linux-nvidia (Ubuntu package) - update to 7.0.0-1013.13
linux-ibm (Ubuntu package) - update to 7.0.0-1009.9
linux-azure-fde (Ubuntu package) - update to 7.0.0-1009.9
linux (Debian package) - update to 6.12.115-2

• https://git.kernel.org/stable/c/6200f41d6fcf2ac7e24866431e381cbc914560e4
• https://git.kernel.org/stable/c/a0d9555bf9eaeba34fe6b6bb86f442fe08ba3842
• https://git.kernel.org/stable/c/ba12c1e578890f6337a415b7dedf476c6d455105

• Off-by-one in Linux kernel ceph
• Ubuntu update for linux
• Ubuntu update for linux-raspi
• Ubuntu update for linux-nvidia
• Ubuntu update for linux-azure
• Debian update for linux