CVE Intelligence
Unknown

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

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.

Published Oct 23, 2026 · Updated Oct 30, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP, GitHub Security Advisories · CNA: Linux

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • EPSS 0.2% (30-day exploitation probability)+1

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
0.18%
ahead of 7% of scored CVEs · Oct 30, 2026
Affects
Linux
Linux
CVSS base
—
Score not published yet.

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Linux Linux).
  2. No fix documented in the sources: reduce exposure and monitor the vendor advisory.
  3. Search available logs for exploit probes, errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Linux Linux version 6de9d08a9718ee9c12ba6343c50141c2d633e3dc≥ 1064f874abc0d05eeed8993815f584d847b72486 and < 361f59e7f3f9a219fb5567bf9abc8482a154a399≥ 1064f874abc0d05eeed8993815f584d847b72486 and < 3f55f71291e4332983cd63b288d1f2be3c9c08fc≥ 1064f874abc0d05eeed8993815f584d847b72486 and < cda0c4e502a0f74a191471ce100fb061e5ab35d6version 4.11≥ 4.10.3 and < 4.11≥ 4.9.15 and < 4.10≥ 4.4.54 and < 4.5
and 9 more ≥ 4.1.40 and < 4.2≥ 1064f874abc0d05eeed8993815f584d847b72486 and < f6394281834492c6516a405a348b545ae698a331version 808e83e5add13152bd4a88346487de68395c136bversion 839d42687dfce0ed0ea2c6bd8d707cc0e276fbe7version 5e6ef5ef6eaf690faad3a7c6c665ebf45d7b6ccf≥ 1064f874abc0d05eeed8993815f584d847b72486 and < 32bf92416614a1e3ff3524fc6b780259c7aad3ef≥ 1064f874abc0d05eeed8993815f584d847b72486 and < 18902a23ef36f83d32bafc58ae2484e6bb4bb8ef≥ 1064f874abc0d05eeed8993815f584d847b72486 and < d73f04e92c1aab78d96ac6cadb234c8a3a373d22≥ 1064f874abc0d05eeed8993815f584d847b72486 and < 6e4012e571867868b545c91ca9d6095fdb709907
Vulnerable CVE Program (cve.org) e CISA ADP

EPSS over time FIRST

Oct 24, 2026 → Oct 30, 2026 · 7 reading(s) · max 0.21%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Not enough vector or weakness data: use the affected application’s logs as a starting point.
application logs

Timeline

What happened to this CVE, newest first.

  • 2026
  • Affected products added · linux/linux
    Oct 30, 2026 · CVE Program (cve.org) e CISA ADP
  • Record published
    Oct 23, 2026
  • Affected products added · linux/linux
    Oct 23, 2026 · CVE Program (cve.org) e CISA ADP
  • Source status changed · → Received
    Oct 23, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 23, 2026 · Alertas do Telegram
  • CVE published
    Oct 23, 2026 · Linux

Source activity

Repeated readings are counted rather than listed.

  • 3× References added · Oct 23, 2026 – Oct 30, 2026
  • 1× Official description updated · Oct 23, 2026 – Oct 23, 2026

References

10 on the record

Elsewhere on this site

Linux
every CVE for this vendor

Related CVEs (same products)

  • CVE-2026-99216 Drivers: hv: Don't reset VMBus connection state on error/exit paths 2d
  • CVE-2026-99215 power: supply: core: prevent unregistering a power supply while a callback runs 2d
  • CVE-2026-99207 scsi: target: Disable interrupts while holding delayed_cmd_lock 2d
  • CVE-2026-99208 drm/xe/oa: Zero OA buffer at allocation 2d
  • CVE-2026-99209 drm/xe: skip eviction of a BO with no resource 2d
  • CVE-2026-99210 accel/rocket: clear rdev on device init failure 2d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No CVSS score published by NVD, the CNA, CISA or GitHub so far.
  • No fixed version, patch or mitigation documented.
  • No CISA SSVC assessment.
  • No CWE classification.
  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-98990 is "namespace: check a submount for references right before unmounting it", rated Unknown. It affects Linux (Linux); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. EPSS 0.18% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

Comments

Moderated technical discussion. Read the community guidelines.

No comments yet.

Sign in or create an account to comment and suggest corrections.