Use of Uninitialized Variable in Linux kernel - CVE-2026-98584

Vulnerability identifier: #VU156887

CSH Severity: Low

CVSS v4: 4.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-98584

CWE-ID: CWE-457

Exploitation vector: Local access

Exploit availability: No public exploit available

The vulnerability allows a local user to disclose uninitialized kernel stack bytes that may contain sensitive information.

The vulnerability exists due to use of an uninitialized stack variable in em_text_dump() in net/sched/em_text.c when handling traffic-control filter dump requests. A local user can request a dump through "tc filter show" or a raw RTM_GETTFILTER request to receive uninitialized bytes because strscpy() leaves trailing bytes in conf.algo[] unwritten and nla_put_nohdr() copies the entire structure into the netlink response.

Linux kernel
Ubuntu
linux (Ubuntu package)
linux-aws (Ubuntu package)
linux-gcp (Ubuntu package)
linux-oracle (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 (Ubuntu package) - update to 7.0.0-42.42
linux-aws (Ubuntu package) - update to 7.0.0-1016.17
linux-gcp (Ubuntu package) - update to 7.0.0-1016.18
linux-oracle (Ubuntu package) - update to 7.0.0-1015.16
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/0b160417826d22f24fc31a5b9cfae3b14aa70f76
• https://git.kernel.org/stable/c/9923e1c537f91f3530b52d4efce85f3d9c131bf8
• https://git.kernel.org/stable/c/9c572a83037a7dcd653ba3a9cc468c16b857d0c9

• Use of Uninitialized Variable in Linux kernel sched
• Ubuntu update for linux-oem-7.0
• Ubuntu update for linux, linux-aws, linux-gcp and more