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CVE-2026-98984— dcache: don't put a mountpoint on a dentry that's being removed

Quick assessment

Affected

Linux Linux

Exploitation

No confirmed in-the-wild exploitation; assess based on exposure

Recommended action

Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

在 Linux 内核中，以下漏洞已得到修复： dcache：不要将挂载点设置在一个正在被删除的 dentry 上、和会先对目标对象调用，然后在锁定该目标 inode 的情况下调用。会获取挂载点的 inode 锁并检查标志，从而确保在执行后不会再出现新的挂载。然而，会为源挂载的根目录创建第二个挂载点，以便将原本位于目标位置的挂载叠加其上。该操作并未锁定任何 inode，而仅拒绝已 unlink（删除链接）的 dentry。在和之间，目标 dentry 仍处于哈希表中：当一个正在被删除的目录

AI Predicted 8.8 Difficulty: Moderate EPSS 0.17% · P6 Updated Oct 23, 2026

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 20

Vendor	Product	Version Range	Status
Linux	Linux	`1064f874abc0d05eeed8993815f584d847b72486< 5e6bfd9f249f2c74bb63c0f06ad959da3bee0971`	affected
		`1064f874abc0d05eeed8993815f584d847b72486< 793cb67b0f52d00c67bd0e76bc57455b5c70ebb8`	affected
		`1064f874abc0d05eeed8993815f584d847b72486< 390ddcea2a8aca411b931a8e2863a80ccca8d2b3`	affected
		`1064f874abc0d05eeed8993815f584d847b72486< 30a1625022411a387cce9239408ece9955bc9c58`	affected
		`1064f874abc0d05eeed8993815f584d847b72486< 75f4197f1e11d2eb75c2d6f916a7d4764db621e5`	affected
		`5e6ef5ef6eaf690faad3a7c6c665ebf45d7b6ccf`	affected
		`839d42687dfce0ed0ea2c6bd8d707cc0e276fbe7`	affected
		`808e83e5add13152bd4a88346487de68395c136b`	affected
… +12 more rows

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Vulnerability Information

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Vulnerability Title

dcache: don't put a mountpoint on a dentry that's being removed

Source: CVE Program / CVE List V5

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: dcache: don't put a mountpoint on a dentry that's being removed rmdir(), unlink() and rename() call dont_mount() on the victim and then detach_mounts() with the victim's inode locked. do_lock_mount() takes the inode lock of the mountpoint and checks cant_mount() so a mount can't show up after detach_mounts(). But attach_recursive_mnt() makes a second mountpoint for the root of the source mount so that the mounts already located at the destination can be put on top of it. No inode is locked for that one and d_set_mounted() only refuses a dentry that is unlinked. Between detach_mounts() and d_delete() the victim is still hashed: rmrace: b passed dont_mount() and detach_mounts(), sleeping T2: move_mount(S, /tmp/plcant/x, BENEATH) = 0 errno 0 () T1: rmdir(/tmp/plcant/d/b) = 0 errno 0 109 107 0:61 /d/b//deleted /tmp/plcant/x rw,relatime - tmpfs tmpfs rw 108 109 0:63 / /tmp/plcant/x rw,relatime - tmpfs T rw A bind mount of the directory that's being removed is moved beneath an existing mount while the rmdir() is located between the two calls. The mount ends up on the removed directory and nothing will ever detach it. Check cant_mount() in d_set_mounted() as well. dont_mount() raises the flag under d_lock before detach_mounts() runs so either the mountpoint is set first and detach_mounts() finds the mount or the flag is seen and the mount is refused.

Source: CVE Program / CVE List V5

CVSS Information

N/A

Source: CVE Program / CVE List V5

Vulnerability Type

N/A

Source: CVE Program / CVE List V5

Affected Products

Vendor	Product	Affected Versions	CPE	Subscribe
Linux	Linux	1064f874abc0d05eeed8993815f584d847b72486 ~ 5e6bfd9f249f2c74bb63c0f06ad959da3bee0971	-
Linux	Linux	4.11	-

II. Public POCs for CVE-2026-98984

#	POC Description	Source Link	Shenlong Link

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III. Intelligence Information for CVE-2026-98984

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Patches & Fixes for CVE-2026-98984 (3)

https://www.cve.org/CVERecord?id=CVE-2026-98984

Same Patch Batch · Linux · 2026-10-23 · 217 CVEs total

CVE-2026-98959	9.8 CRITICAL	btrfs: fix xattr replace when multiple xattrs are packed in the same item
CVE-2026-99078	9.8 CRITICAL	net/mlx5e: Prevent stale XSK buffer release on MPWQE refill retry
CVE-2026-99079	9.8 CRITICAL	net/mlx5e: Prevent stale XSK buffer release on refill retry
CVE-2026-98988	8.8 HIGH	namespace: keep covered mounts covered in OPEN_TREE_NAMESPACE
CVE-2026-99083	8.8 HIGH	ksmbd: fix heap out-of-bounds write in krb5_authenticate()
CVE-2026-99082	8.8 HIGH	KVM: x86: Use active memslots for the per-vCPU MMIO cache
CVE-2026-98870	8.8 HIGH	ksmbd: remove stale channels from all sessions on teardown
CVE-2026-98980	8.8 HIGH	namei: don't reveal overmounted entries in refwalk
CVE-2026-98981	8.8 HIGH	namespace: unhash a dentry before detaching the mounts on it
CVE-2026-99042	8.4 HIGH	io_uring/net: populate CONNECT filter fields for 24-byte sockaddr_in6
CVE-2026-98978	8.4 HIGH	namespace: never expire a locked mount
CVE-2026-99064	8.1 HIGH	cipso: adjust cached option offsets when removing CIPSO
CVE-2026-98968	8.1 HIGH	amt: send the relay's General Query directly from the receive path
CVE-2026-98944	7.8 HIGH	HID: steam: Refactor registration
CVE-2026-99053	7.8 HIGH	tipc: hold a reference to nodes found by link name
CVE-2026-99054	7.8 HIGH	tipc: destroy topsrv workqueues before closing connections
CVE-2026-99056	7.8 HIGH	strparser: make sure __strp_recv isn't running before tearing down the parser
CVE-2026-99002	7.8 HIGH	drm/vmwgfx: validate pitch coming from userspace
CVE-2026-98899	7.8 HIGH	netfilter: ipset: mark the rcu locked areas properly
CVE-2026-99006	7.8 HIGH	drm/i915/gem: Prevent overstepping exec array boundary

Showing top 20 of 217 CVEs. View all on vendor page → →

IV. Related Vulnerabilities

Same product: Linux

Same vendor: Linux