CVE-2025-31133
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2025-11-06

Last updated on: 2025-12-03

Assigner: GitHub, Inc.

Description
runc is a CLI tool for spawning and running containers according to the OCI specification. In versions 1.2.7 and below, 1.3.0-rc.1 through 1.3.1, 1.4.0-rc.1 and 1.4.0-rc.2 files, runc would not perform sufficient verification that the source of the bind-mount (i.e., the container's /dev/null) was actually a real /dev/null inode when using the container's /dev/null to mask. This exposes two methods of attack: an arbitrary mount gadget, leading to host information disclosure, host denial of service, container escape, or a bypassing of maskedPaths. This issue is fixed in versions 1.2.8, 1.3.3 and 1.4.0-rc.3.
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Meta Information
Published
2025-11-06
Last Modified
2025-12-03
Generated
2026-06-16
AI Q&A
2025-11-06
EPSS Evaluated
2026-06-15
NVD
CVE-2025-31133
Affected Vendors & Products
Showing 4 associated CPEs
Vendor Product Version / Range
linuxfoundation runc to 1.2.8 (exc)
linuxfoundation runc From 1.3.0 (inc) to 1.3.3 (exc)
linuxfoundation runc 1.4.0
linuxfoundation runc 1.4.0
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-363 The product checks the status of a file or directory before accessing it, which produces a race condition in which the file can be replaced with a link before the access is performed, causing the product to access the wrong file.
CWE-61 The product, when opening a file or directory, does not sufficiently account for when the file is a symbolic link that resolves to a target outside of the intended control sphere. This could allow an attacker to cause the product to operate on unauthorized files.
Attack-Flow Graph
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Executive Summary

This vulnerability in runc occurs because the tool does not sufficiently verify that the source of a bind-mount, specifically the container's /dev/null, is actually a real /dev/null inode. This allows attackers to use the container's /dev/null to mask other mounts, enabling arbitrary mount gadgets. As a result, attackers can cause host information disclosure, host denial of service, container escape, or bypass maskedPaths protections.

Impact Analysis

The vulnerability can lead to serious impacts including disclosure of sensitive host information, denial of service on the host system, escape from the container environment to the host, and bypassing of security mechanisms like maskedPaths. These impacts can compromise the security and stability of containerized environments and the underlying host.

Mitigation Strategies

Upgrade runc to version 1.2.8, 1.3.3, or 1.4.0-rc.3 or later, as these versions contain the fix for this vulnerability.

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