VULNpocalypse

CVE-2025-31133: runc container escape via “masked path” abuse due to mount race conditions

Advisory generated from the CVE record, CISA, Exploit Observer and VEDAS: what it is, whether it is exploited, who is affected, and how to fix and detect it.

Generated by VEDAS. Scores as of 2026-11-01 19:19 UTC. Rebuilt every few hours from cve-scores, CISA KEV and vedas-signatures. How this works and its limits.

What it is

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.

Description quoted from the CVE record (assigned by GitHub_M, published 2025-11-06).

Weakness: CWE-61: UNIX Symbolic Link (Symlink) Following; CWE-363: Race Condition Enabling Link Following

How it can be exploited

Exploitable with local access with low attack complexity only when specific conditions are present needing low privileges and a user must actively take an action. Impact: confidentiality high, integrity high, availability 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

CISA assessment (SSVC): CISA has no evidence of exploitation. Automatable: no. Technical impact: total.

Public exploit evidence (Exploit Observer)

Also known as: BDU:2025-14041, CNNVD-202511-518, EUVD-2025-37944, EUVD-2025-37945, GHSA-9493-h29p-rfm2, GHSA-cgrx-mc8f-2prm, GHSA-qw9x-cqr3-wc7r

VEDAS cluster: VEDAS:BEASTVANGUARD

Exploit Observer links 4 pieces of public exploit code or detection modules that name this CVE or one of its aliases.

Exploit code and modules (4)

Code that names this CVE. A repository can be a working exploit, a scanner, a fake or malware; read it before running anything.

Vulnerability databases and vendor advisories (16)

Catalogue entries, not exploit evidence.

133 more references returned by Exploit Observer did not name this CVE or an alias, so they are left out.

VEDAS data as of 2026-11-01T17:12 UTC; fetched 2026-11-02.

Live scores

EPSS
0.012
some chance of attack soon
VEDAS
0.905
strong exploit evidence
On CISA KEV
Not listed
Detection rule
Out of scope (local)

Who is affected

ProductAffectedNot affected
opencontainers runcversion < 1.2.8
version >= 1.3.0-rc.1, < 1.3.3
version >= 1.4.0-rc.1, <= 1.4.0-rc.3		Not stated

Version ranges exactly as the CVE record states them. “Before X” means X is the first fixed version.

Exploit Observer also maps it to: linuxfoundation runc, ао_«нтц_ит_роса» роса_хром, ооо_«ред_софт» ред_ос, ооо_«русбитех-астра» платформа_контейнеризации_«боцман», сообщество_свободного_программного_обеспечения runc.

How to fix it

No fixed version or vendor advisory is listed in the CVE record yet. Watch the vendor’s security page.

How to detect it

This bug needs local access to exploit. VEDAS signatures cover remotely exploitable bugs for now, so there is no network rule or remote check for it. Patch it and watch your endpoint telemetry for unusual local activity.

Advisories on this CVE

References

Other references

Other databases

Where this comes from

This advisory is generated automatically by VEDAS from: CVE.org record, cve-scores (EPSS and VEDAS), Exploit Observer. Text in quotes is reproduced from the source; everything else is a fixed template filled with source fields. Nothing here is written by a language model. Check the vendor advisory before acting, and read how VEDAS and Exploit Observer work, and their limits.