Critical File handling

CVE-2026-47243 — Kata guest escape: runtime-rs guest-root to host-root escape via virtiofs

Kata Containers is an open source project focusing on a standard implementation of lightweight Virtual Machines (VMs) that perform like containers. Prior to 3.31.0, the runtime-rs standalone virtio-fs path is vulnerable to a guest-root to host-root escape. In this configuration, Kata runs the host virtiofsd as root with --sandbox none --seccomp none, so an attacker with root-equivalent access inside the guest can bypass the guest virtio-fs client entirely by taking over the virtio-fs PCI device and building a virtqueue in userspace to submit raw FUSE requests directly to the host virtiofsd. A crafted FUSE_SYMLINK request whose new symlink name is an absolute host path is honored outside the configured shared directory, allowing guest root to create root-owned symlinks in sensitive host locations such as /etc/cron.d. By pointing such a symlink at a guest-controlled crontab payload reachable through a live runtime process's mount namespace, the attacker causes the host cron daemon to execute that payload as host root, crossing the Kata isolation boundary. This issue is fixed in version 3.31.0.

Published Aug 7, 2026 · Updated Oct 15, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: GitHub_M

Low

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

Technical severity (critical)+10
CISA SSVC: exploitation "poc"+5

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

—

No EPSS score.

Affects

Katacontainers

Kata Containers

CVSS base

9.2

Critical · 2 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

Proof of concept

none · proof-of-concept · active

Automatable

can an attacker script the kill-chain steps

Technical impact

Total

partial · total control of the vulnerable component

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.

Identify exposed assets running the affected vendor/product/version combinations (Katacontainers Kata Containers).
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
Search available logs for exploit probes matching the vulnerability class (file handling), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Katacontainers	Kata Containers	version < 3.31.0	Vulnerable	CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Local

Attack complexity

Low

Attack requirements

None

Privileges required

High

User interaction

None

Scope

Confidentiality (vulnerable system)

High

Integrity (vulnerable system)

High

Availability (vulnerable system)

None

Confidentiality (subsequent)

High

Integrity (subsequent)

High

Availability (subsequent)

None

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
9.2	CVSS 4.0	Critical	—	—	security-advisories@github.com via NIST National Vulnerability Database
9.2	CVSS 4.0	Critical	—	—	GitHub_M via CVE Program (cve.org) e CISA ADP

CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

(score shown at the top: security-advisories@github.com)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-22 · Path Traversal

Other CVEs with this weakness →

Detection

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

Local/physical vector: focus on endpoint telemetry (EDR) from affected hosts.
Monitor file creation in web directories and paths with traversal sequences (../).

endpoint telemetry (EDR)file integrity (FIM)

Timeline

What happened to this CVE, newest first.

2026
Affected products added · kata-containers/kata-containers
Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 15, 2026
CVSS changed · 9.2
Oct 15, 2026 · NIST National Vulnerability Database
Source status changed · → Deferred
Oct 15, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 15, 2026 · NIST National Vulnerability Database
CVE published
Aug 7, 2026 · GitHub_M

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 15, 2026 – Oct 15, 2026

References

2 on the record

www.openwall.com/lists/oss-security/2026/05/21/14
NIST National Vulnerability Database
github.com/kata-containers/kata-containers/security/advisories/GHSA-2gv2-cffp-j2
x_refsource_CONFIRM, NIST National Vulnerability Database

Elsewhere on this site

Katacontainers
every CVE for this vendor

File handling
same class

CWE-22
other pages naming this weakness

Related CVEs (same products)

Medium CVE-2026-64676 Kata Containers: Unauthorized mem-agent ttRPC methods let an untrusted host tamper with confidential-guest memory Aug 7, 2026
Critical CVE-2026-50540 Kata Containers: Config Path Annotation Arbitrary File Loading Aug 7, 2026
Critical CVE-2026-44210 Kata Containers have VM Escape via virtiofsd Argument Injection through Default-Enabled Pod Annotations Jul 23, 2026
High CVE-2026-41326 Kata Containers: CopyFile Policy Subversion via Symlinks Apr 24, 2026
High CVE-2026-24834 Kata Container to Guest micro VM privilege escalation Feb 19, 2026
Critical CVE-2026-24054 Kata Containers: improper handling of empty rootfs triggers host block device hotplug Jan 29, 2026

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 FIRST EPSS score.
No fixed version, patch or mitigation documented.
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-2026-47243 is "Kata guest escape: runtime-rs guest-root to host-root escape via virtiofs", rated Critical. It affects Kata Containers (Katacontainers); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 9.2 describes technical severity. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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