PT-2026-39078 · Linux · Linux Kernel

Jiri + 1 · Published 2026-05-08 · Updated 2026-05-24 · CVE-2026-43417

Positive Technologies (AI Summary)

CVSS v3.1

5.5

Medium

Base vector

AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Name of the Vulnerable Software and Affected Versions Linux kernel (affected versions not specified)

Description An issue exists in the sched/mmcid component regarding the handling of vfork() and CLONE VM. A logic error occurs when the number of tasks associated with a process is smaller than the number of MMCID users. The system incorrectly accounts for already processed tasks while searching the task list for a vfork()ed task. If this leads to the number of tasks to be handled reaching zero, the walk stops without fixing the vfork()ed task's CID. This results in a failure to acquire a transitional CID during a subsequent schedule in, causing the machine to stall. This can lead to a state where a task endlessly loops in the mm get cid() function.

Recommendations At the moment, there is no information about a newer version that contains a fix for this vulnerability.

Related Identifiers

CVE-2026-43417

Affected Products

Linux Kernel

References · 13

• https://osv.dev/vulnerability/DEBIAN-CVE-2026-43417 · Vendor Advisory
• https://ubuntu.com/security/CVE-2026-43417 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-43417 · Security Note
• https://osv.dev/vulnerability/UBUNTU-CVE-2026-43417 · Vendor Advisory
• https://cve.org/CVERecord?id=CVE-2026-43417 · Security Note
• https://security-tracker.debian.org/tracker/CVE-2026-43417 · Vendor Advisory
• https://twitter.com/hetmehtaa/status/2055151398283837677 · Twitter Post
• https://twitter.com/CVEnew/status/2052767659507503447 · Twitter Post
• https://t.me/cveNotify/164646 · Telegram Post
• https://twitter.com/dailycve/status/2058343824536023167 · Twitter Post
• https://git.kernel.org/stable/c/e6761cdce78a8919a537989afb6aaf6881469f83 · Note
• https://git.kernel.org/stable/c/28b5a1395036d6c7a6c8034d85ad3d7d365f192c · Note
• https://git.kernel.org/linus/28b5a1395036d6c7a6c8034d85ad3d7d365f192c · Note