CVE-2025-31133

Container escape via raced /dev/null bind mount

Published Nov 6, 2025 · Updated Nov 6, 2025

Symlink race in OCI runc before 1.2.8, 1.3.0-rc.1 through 1.3.2, and 1.4.0-rc.1 through 1.4.0-rc.2 allows local users to escape containers. During maskedPaths setup, runc bind-mounts the container's /dev/null without ensuring the source remains the real device inode, so a shared-mount race can substitute a symlink to a procfs target or delete the source and suppress masking. Local users must control container creation or parallel containers with shared mounts; non-user-namespaced root containers expose host data, service interruption, or host code execution.

CVSS severity7.3
High
EPSS probability0.84%
Next 30 days · Sep 17, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Symlink race in OCI runc before 1.2.8, 1.3.0-rc.1 through 1.3.2, and 1.4.0-rc.1 through 1.4.0-rc.2 allows local users to escape containers. During maskedPaths setup, runc bind-mounts the container's /dev/null without ensuring the source remains the real device inode, so a shared-mount race can substitute a symlink to a procfs target or delete the source and suppress masking. Local users must control container creation or parallel containers with shared mounts; non-user-namespaced root containers expose host data, service interruption, or host code execution.

The record

CVE
CVE-2025-31133
Published
Nov 6, 2025
Updated
Nov 6, 2025
Vendor
Open Container Initiative
Product
runc
Classifications
CWE-61, CWE-363, T1611
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Nov 6, 2025CVE publishedPublication date reported by the CVE source.
  2. Nov 6, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 1.2.8
  2. Affected versionversion=>= 1.3.0-rc.1, < 1.3.3
  3. Affected versionversion=>= 1.4.0-rc.1, <= 1.4.0-rc.3

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Open Container Initiative · runcversion=< 1.2.8; version=>= 1.3.0-rc.1, < 1.3.3; version=>= 1.4.0-rc.1, <= 1.4.0-rc.3

Published CVSS scores

7.3GitHub, Inc.CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:A/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
7.8NIST National Vulnerability DatabaseCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-61UNIX Symbolic Link (Symlink) Following
CWE-363Race Condition Enabling Link Following
T1611Escape to Host

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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