CVE-2026-15788

Host file disclosure via unresolved NTFS junctions

Published Jul 20, 2026 · Updated Jul 20, 2026

Information disclosure in Moby BuildKit before 0.31.2 allows local users to read arbitrary host files through a WCOW cache mount. The cache mount source= selector accepts a path inside the cache root without detecting that an NTFS directory junction resolves outside that root. Exploitation requires an untrusted build to run on a WCOW-configured daemon; the reported consequence is host-file disclosure only.

CVSS severity5.6
Medium
EPSS probability0.27%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Information disclosure in Moby BuildKit before 0.31.2 allows local users to read arbitrary host files through a WCOW cache mount. The cache mount source= selector accepts a path inside the cache root without detecting that an NTFS directory junction resolves outside that root. Exploitation requires an untrusted build to run on a WCOW-configured daemon; the reported consequence is host-file disclosure only.

The record

CVE
CVE-2026-15788
Published
Jul 20, 2026
Updated
Jul 20, 2026
Vendor
Moby Project
Product
BuildKit
Classifications
CWE-59, T1005
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 20, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=0 <0.31.2

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Moby Project · BuildKitversion=0 <0.31.2

Published CVSS scores

5.6Docker Inc.CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-59Improper Link Resolution Before File Access ('Link Following')
T1005Data from Local System

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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo