VulnerabilityPublished 23 Oct 2026

CVE-2026-98989: Linux kernel · namespace: check a recursive bind mount for mount namespace loops

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in c640a01a78e42302879006ed7b7d5a9a943ba815 : update Linux kernel when convenient.

Data as of 26 Oct 2026, 13:07 UTC

Severity

Medium

Rated Medium by Threat Radar's AI analysis · CVSS not yet scored by NVD

EPSS: 0.1% chance of exploitation in 30 days – higher than 5% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in c640a01a78e42302879006ed7b7d5a9a943ba815, a0ba48256f5dff6f75a45f8ce39fe57f21df1022, 37a82f400efa4d263542a5fa41755b21057f1e5d

Exploitation evidence

Disclosed: evidence found.
CVE published 23 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade Linux kernel to c640a01a78e42302879006ed7b7d5a9a943ba815, a0ba48256f5dff6f75a45f8ce39fe57f21df1022 or 37a82f400efa4d263542a5fa41755b21057f1e5d.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ e149ed2b805fefdccf7ccdfc19eca22fdd4514ac, < c640a01a78e42302879006ed7b7d5a9a943ba815	Fixed in c640a01a78e42302879006ed7b7d5a9a943ba815
LinuxLinux	Affected ≥ e149ed2b805fefdccf7ccdfc19eca22fdd4514ac, < a0ba48256f5dff6f75a45f8ce39fe57f21df1022	Fixed in a0ba48256f5dff6f75a45f8ce39fe57f21df1022
LinuxLinux	Affected ≥ e149ed2b805fefdccf7ccdfc19eca22fdd4514ac, < 37a82f400efa4d263542a5fa41755b21057f1e5d	Fixed in 37a82f400efa4d263542a5fa41755b21057f1e5d
LinuxLinux	Affected =3.19	Fixed in–

AI-suggested

This vulnerability has been fixed in the Linux kernel by applying cycle detection checks to the entire recursive bind mount tree before it is grafted. Users should update to a Linux kernel version that includes the fixes identified by commits c640a01a78e42302879006ed7b7d5a9a943ba815, a0ba48256f5dff6f75a45f8ce39fe57f21df1022, and 37a82f400efa4d263542a5fa41755b21057f1e5d. No other mitigation is indicated.

Description

CVE-2026-98989 is a Linux kernel vulnerability involving recursive bind mounts that can create mount namespace loops. The kernel's do_loopback() function does not fully check for cycles when performing recursive bind mounts with MS_REC, allowing a process to create a bind-mount stack of mount namespace file descriptors that leaks mount namespaces and mounts indefinitely. This can cause excessive memory consumption due to unbounded mount namespace leaks. The issue affects Linux kernel version 3.19 and was fixed in specific commits.

Impact

An attacker with the ability to create bind mounts can cause the kernel to leak mount namespaces and mounts indefinitely, leading to increased memory usage (noted as a large increase in Shmem usage). This could degrade system stability or cause denial of service due to resource exhaustion. There is no indication of privilege escalation or code execution from the provided data.

Summary

The vulnerability arises because do_loopback() only checks the starting dentry for cycles but does not verify the entire recursive bind mount tree when MS_REC is used. This allows a process to bind mount mount namespace files from other namespaces without proper cycle detection, leading to mount namespace leaks and potentially unbounded resource consumption. The kernel now applies the same check_for_nsfs_mounts() validation to the copied tree before grafting it to prevent such cycles.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 26 Oct 2026, 09:55 UTC

Technical details

References

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