CVE-2025-31133 | runc container escape via "masked path" abuse due to mount race conditions

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.

Published: 2025-11-06 Last update: 2025-12-03 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2025-31133 is rated Low Risk (29.5/100): CVSS High severity, with low exploitation likelihood (EPSS 0.01%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2025-31133

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2025-11-07 — 0.01% —

Full EPSS history (1 record total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-31133

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.3 4.0 HIGH
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/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 Click to expand
Attack vector (AV:L)
Attacker needs local access on the target system.
Attack complexity (AC:L)
Exploitation conditions are straightforward and stable.
Attack requirements (AT:P)
Additional preconditions must be present for exploitation.
Privileges required (PR:L)
Low privileges are required.
User interaction (UI:A)
User interaction is required in an active way.
Vulnerable system confidentiality impact (VC:H)
High confidentiality impact on the vulnerable system.
Vulnerable system integrity impact (VI:H)
High integrity impact on the vulnerable system.
Vulnerable system availability impact (VA:H)
High availability impact on the vulnerable system.
Subsequent system confidentiality impact (SC:H)
High confidentiality impact on subsequent systems.
Subsequent system integrity impact (SI:H)
High integrity impact on subsequent systems.
Subsequent system availability impact (SA:H)
High availability impact on subsequent systems.
Exploit maturity (threat) (E:X)
Not defined: no reliable threat intelligence; scoring assumes the worst case (equivalent to Attacked).
Confidentiality requirement (CR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Integrity requirement (IR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Availability requirement (AR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Modified attack vector (MAV:X)
Not defined: scoring uses the Base Attack Vector (AV).
Modified attack complexity (MAC:X)
Not defined: scoring uses the Base Attack Complexity (AC).
Modified attack requirements (MAT:X)
Not defined: scoring uses the Base Attack Requirements (AT).
Modified privileges required (MPR:X)
Not defined: scoring uses the Base Privileges Required (PR).
Modified user interaction (MUI:X)
Not defined: scoring uses the Base User Interaction (UI).
Modified vulnerable system confidentiality impact (MVC:X)
Not defined: scoring uses the Base VC metric.
Modified vulnerable system integrity impact (MVI:X)
Not defined: scoring uses the Base VI metric.
Modified vulnerable system availability impact (MVA:X)
Not defined: scoring uses the Base VA metric.
Modified subsequent system confidentiality impact (MSC:X)
Not defined: scoring uses the Base SC metric.
Modified subsequent system integrity impact (MSI:X)
Not defined: scoring uses the Base SI metric.
Modified subsequent system availability impact (MSA:X)
Not defined: scoring uses the Base SA metric.
Safety (supplemental) (S:X)
Not evaluated.
Automatable (supplemental) (AU:X)
Not evaluated.
Recovery (supplemental) (R:X)
Not evaluated.
Value density (supplemental) (V:X)
Not evaluated.
Vulnerability response effort (supplemental) (RE:X)
Not evaluated.
Provider urgency (supplemental) (U:X)
Not evaluated.
 — — [email protected]
7.8 3.1 HIGH
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 1.1 6.0 [email protected]

Weakness enumeration for CVE-2025-31133

GitHub Security Advisory for CVE-2025-31133

GHSA-9493-h29p-rfm2 · Severity: high · Ecosystem: go — runc container escape via "masked path" abuse due to mount race conditions

OS Trackers for CVE-2025-31133

vendor priority summary link
alpine — CVE-2025-31133: 1 source package rows (runc); 54 state rows across 3 repos (3.22-community, 3.23-community, edge-community); fixed 12, open 42. https://security.alpinelinux.org/vuln/CVE-2025-31133
debian not yet assigned CVE-2025-31133 not yet assigned priority: Debian including 1 source packages (runc), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): open 3, resolved 2. https://security-tracker.debian.org/tracker/CVE-2025-31133
redhat high — https://access.redhat.com/security/cve/CVE-2025-31133
suse high CVE-2025-31133 severity important: SUSE including 463 source package names (2.0.4-5.5.402:podman-4.9.5-150500.3.56.2, 2.0.4-5.5.402:runc-1.3.3-150000.85.1, …), 1554 product×package rows across 278 product lines (Container suse/sl-micro/6.0/baremetal-os-container, Container suse/sl-micro/6.0/base-os-container, … (278 product lines)): Known Not Affected 761, Fixed 555, Known Affected 231, First Fixed 7. https://www.suse.com/security/cve/CVE-2025-31133/
ubuntu high CVE-2025-31133 high priority: Ubuntu including 3 source packages (runc, runc-app, runc-stable), 22 status rows across 9 suites (bionic, focal, jammy, noble, plucky, questing, trusty, upstream, xenial): ignored 8, released 8, DNE 6. https://ubuntu.com/security/CVE-2025-31133

Affected software / configurations for CVE-2025-31133

Vendor Product Version Raw CPE
linuxfoundation runc < 1.2.8 cpe:2.3:a:linuxfoundation:runc:*:*:*:*:*:*:*:*
linuxfoundation runc >= 1.3.0, < 1.3.3 cpe:2.3:a:linuxfoundation:runc:*:*:*:*:*:*:*:*
linuxfoundation runc 1.4.0 cpe:2.3:a:linuxfoundation:runc:1.4.0:rc1:*:*:*:*:*:*
linuxfoundation runc 1.4.0 cpe:2.3:a:linuxfoundation:runc:1.4.0:rc2:*:*:*:*:*:*

References for CVE-2025-31133

cvelogic Threat Intelligence