Untrusted Pointer Dereference in Linux kernel - CVE-2026-99016

Vulnerability identifier: #VU157487

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-2026-99016

CWE-ID: CWE-822

Exploitation vector: Local access

Exploit availability: No public exploit available

The vulnerability allows a local user to read and modify arbitrary kernel memory, potentially causing a denial of service.

The vulnerability exists due to untrusted pointer dereference in the RISC-V arch_futex_atomic_op_inuser() and futex_atomic_cmpxchg_inatomic() helpers when processing tagged user pointers with the tagged-address ABI enabled. A local user can supply a crafted tagged pointer to FUTEX_WAKE_OP that passes validation after tag removal but retains its tag during the atomic access, causing an atomic read-modify-write on a kernel address and using the comparison result as a read oracle to disclose kernel memory contents.

The described overlap between tag bits and canonical-address bits occurs with Sv57 and PMLEN=16.

Linux kernel
Ubuntu
linux (Ubuntu package)
linux-realtime (Ubuntu package)
linux-oracle (Ubuntu package)
linux-aws (Ubuntu package)
linux-gcp (Ubuntu package)
linux-azure (Ubuntu package)
linux-raspi (Ubuntu package)
linux-ibm (Ubuntu package)
linux-oracle-7.0 (Ubuntu package)
linux-gcp-7.0 (Ubuntu package)
linux-azure-fde-7.0 (Ubuntu package)
linux-oem-7.0 (Ubuntu package)
linux-gke (Ubuntu package)
linux-azure-fde (Ubuntu package)
linux-aws-7.0 (Ubuntu package)

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
linux (Ubuntu package) - update to 7.0.0-43.43
linux-realtime (Ubuntu package) - update to 7.0.0-43.43.1
linux-oracle (Ubuntu package) - update to 7.0.0-1016.18
linux-aws (Ubuntu package) - update to 7.0.0-1017.18
linux-gcp (Ubuntu package) - update to 7.0.0-1017.19
linux-azure (Ubuntu package) - update to 7.0.0-1020.21
linux-raspi (Ubuntu package) - update to 7.0.0-1023.23
linux-ibm (Ubuntu package) - update to 7.0.0-1018.18
linux-oracle-7.0 (Ubuntu package) - update to 7.0.0-1016.18~24.04.1
linux-gcp-7.0 (Ubuntu package) - update to 7.0.0-1017.19~24.04.1
linux-azure-fde-7.0 (Ubuntu package) - update to 7.0.0-1019.19~24.04.1
linux-oem-7.0 (Ubuntu package) - update to 7.0.0-1018.18
linux-gke (Ubuntu package) - update to 7.0.0-1010.11
linux-azure-fde (Ubuntu package) - update to 7.0.0-1019.19
linux-aws-7.0 (Ubuntu package) - update to 7.0.0-1017.18~24.04.1

• https://git.kernel.org/stable/c/2e5c80bbc062a8dda33e687ebf7be8f074ee4f7d
• https://git.kernel.org/stable/c/405290be962b32eec842776fbe3bdf81f15b1676
• https://git.kernel.org/stable/c/8e48d8d51ab37b7decfbff3e2844e027a52ad6ea

• Untrusted Pointer Dereference in Linux kernel include asm
• Ubuntu update for linux, linux-aws, linux-gcp and more
• Ubuntu update for linux-azure
• Ubuntu update for linux-aws-7.0, linux-azure-fde, linux-azure-fde-7.0 and more
• Ubuntu update for linux-raspi