CVE-2026-98988 — namespace: keep covered mounts covered in OPEN_TREE_NAMESPACE

Affected: Linux

In the Linux kernel, the following vulnerability has been resolved:

namespace: keep covered mounts covered in OPEN_TREE_NAMESPACE

open_tree(OPEN_TREE_NAMESPACE) creates a new mount namespace from a copy of the tree at the given path. The caller needs to be privileged over its current user namespace because the new mount namespace will be owned by it. It doesn't need to be privileged over the mount namespace the tree is copied from. An unprivileged user just needs to create a user namespace first.

The copy follows the rules of a detached bind mount. Without AT_RECURSIVE only the mount itself is cloned and its children are left out. With AT_RECURSIVE unbindable mounts are skipped. Both is fine when the caller has privileges over the source mount namespace because it could unmount those mounts anyway. Not so for an unprivileged user in that mount namespace. For them a mount namespace copy is what unshare() does. copy_mnt_ns() copies everything including unbindable mounts and lock_mnt_tree() makes sure nothing can be unmounted in the copy. Nothing that was covered gets revealed.

create_new_namespace() only does the locking and so the covered content is right there in the new mount namespace:

# mount -t tmpfs none /tmp/otn; mkdir /tmp/otn/covered # echo hidden > /tmp/otn/covered/under.txt # mount -t tmpfs none /tmp/otn/covered

uid 1000, after unshare(CLONE_NEWUSER): fd = open_tree(AT_FDCWD, "/tmp/otn", OPEN_TREE_NAMESPACE); setns(fd, CLONE_NEWNS); open("/cover…

USN-9018-1 — linux, linux-aws, linux-gcp, linux-ibm, linux-oem-7.0, linux-oracle vulnerabilities

Affected: Ubuntu:26.04:LTS: linux, Ubuntu:26.04:LTS: linux-aws, Ubuntu:26.04:LTS: linux-gcp, Ubuntu:26.04:LTS: linux-ibm, Ubuntu:26.04:LTS: linux-oem-7.0, Ubuntu:26.04:LTS: linux-oracle

Several security issues were discovered in the Linux kernel. An attacker could possibly use these to compromise the system. This update corrects flaws in the following subsystems: - Network file systems library; - Stream parser; - ARM64 architecture; - PowerPC architecture; - RISC-V architecture; - S390 architecture; - User-Mode Linux (UML); - x86 architecture; - Block layer subsystem; - Android drivers; - Bluetooth drivers; - TPM device driver; - DPLL subsystem; - EDAC drivers; - GPIO subsystem; - GPU drivers; - HID subsystem; - IIO subsystem; - IIO ADC drivers; - InfiniBand drivers; - Input Device (Miscellaneous) drivers; - Multiple devices driver; - MemoryStick subsystem; - MMC subsystem; - MTD block device drivers; - Network drivers; - Ethernet bonding driver; - Mellanox network drivers; - STMicroelectronics network drivers; - Ethernet team driver; - MediaTek network drivers; - NVME drivers; - Device tree and open firmware driver; - Power sequencing drivers; - Voltage and Current Regulator drivers; - Real Time Clock drivers; - SCSI subsystem; - Greybus lights staging drivers; - Trusted Execution Environment drivers; - Thunderbolt and USB4 drivers; - TTY drivers; - Cadence USB3 driver; - USB Device Class drivers; - USB core drivers; - DesignWare USB2 driver; - DesignWare USB3 driver; - USB Gadget drivers; - USB Serial drivers; - USB Mass Storage drivers; - USB Type-C suppor…

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CVE-2026-98988 — namespace: keep covered mounts covered in OPEN_TREE_NAMESPACE

USN-9018-1 — linux, linux-aws, linux-gcp, linux-ibm, linux-oem-7.0, linux-oracle vulnerabilities