Goal Reached Thanks to every supporter — we hit 100%!

Goal: 1000 CNY · Raised: 1359 CNY

100%

Buy Us a Coffee

CVE-2026-98990— namespace: check a submount for references right before unmounting it

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：命名空间（namespace）：在卸载子挂载点之前，检查其引用计数。和函数首先收集所有允许卸载的挂载点，随后执行卸载操作。某个挂载点是否处于“繁忙”状态，由在挂载树上进行判断。然而，卸载第一个挂载点会改变第二个挂载点所传播到的树结构。会将一个幸存的覆盖挂载（overmount）从其正在卸载的副本上移走，并将其挂载到该副本原先所在的位置。如果此时第二个目标挂载点的传播副本恰好在该位置被查找，那么这个覆盖挂载就会被视为第二次的候选对象。由于该覆盖挂载没有子挂载点

AI Predicted 7.8 Difficulty: Moderate EPSS 0.18% · P7 Updated Oct 23, 2026

Possible ATT&CK Techniques 2 AI

T1212 · Exploitation for Credential Access T1068 · Exploitation for Privilege Escalation

Affected Version Matrix 20

Vendor	Product	Version Range	Status
Linux	Linux	`1064f874abc0d05eeed8993815f584d847b72486< f6394281834492c6516a405a348b545ae698a331`	affected
		`1064f874abc0d05eeed8993815f584d847b72486< 6e4012e571867868b545c91ca9d6095fdb709907`	affected
		`1064f874abc0d05eeed8993815f584d847b72486< d73f04e92c1aab78d96ac6cadb234c8a3a373d22`	affected
		`1064f874abc0d05eeed8993815f584d847b72486< 18902a23ef36f83d32bafc58ae2484e6bb4bb8ef`	affected
		`1064f874abc0d05eeed8993815f584d847b72486< 32bf92416614a1e3ff3524fc6b780259c7aad3ef`	affected
		`5e6ef5ef6eaf690faad3a7c6c665ebf45d7b6ccf`	affected
		`839d42687dfce0ed0ea2c6bd8d707cc0e276fbe7`	affected
		`808e83e5add13152bd4a88346487de68395c136b`	affected
… +12 more rows

Get alerts for future matching vulnerabilities Log in to subscribe

Vulnerability Information

Have questions about the vulnerability? See if Shenlong's analysis helps!

View Shenlong Deep Dive ↗

Although we use advanced large model technology, its output may still contain inaccurate or outdated information.Shenlong tries to ensure data accuracy, but please verify and judge based on the actual situation.

Vulnerability Title

namespace: check a submount for references right before unmounting it

Source: CVE Program / CVE List V5

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: namespace: check a submount for references right before unmounting it shrink_submounts() and mark_mounts_for_expiry() first collect all the mounts they are allowed to unmount and then unmount them. Whether a mount is busy is decided by propagate_mount_busy() on the tree. But unmounting the first mount changes the tree that the second one propagates into. propagate_umount() moves a surviving overmount off a copy it unmounts and mounts it where the copy was mounted. If that's where the propagated copy of the second victim is looked up the overmount becomes a candidate of the second umount_tree(). It's childless and so trim_one() commits it without looking at its reference count. So a synchronous umount pulls out a busy mount that is in use somewhere else and marks it MNT_SYNC_UMOUNT while it has users: umount2(/tmp/plshrink/p1, 0) = 0 errno 0 cwd is (unreachable) The same two umounts requested one after the other fail with EBUSY. This needs a mount with MNT_SHRINKABLE, i.e., automounted submounts of NFS, AFS and CIFS or the tracefs mount below debugfs. Bind mounts inherit the flag. Check each mount right before it is unmounted under the same hold of namespace_sem and mount_lock as the umount itself. Make sure that the algorithm stays linear.

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 ~ f6394281834492c6516a405a348b545ae698a331	-
Linux	Linux	4.11	-

II. Public POCs for CVE-2026-98990

#	POC Description	Source Link	Shenlong Link

AI-Generated POC Premium

No public POC found.

III. Intelligence Information for CVE-2026-98990

请登录查看更多情报信息。

Patches & Fixes for CVE-2026-98990 (4)

https://www.cve.org/CVERecord?id=CVE-2026-98990

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