BuildKit's cache mount source= selector on Windows Container on Windows (WCOW) workers does not detect NTFS directory junctions placed inside the cache root. A build authored by an untrusted user on a WCOW-configured BuildKit daemon can read arbitrary host files reachable to the BuildKit daemon process.
CVE-2026-15788
This medium-severity CVE scores 5.6 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.1%, top 96% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
- Lower severity and no public exploit yet
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 5.6
- EG Score
- 5.6(medium)
- EG Risk
- 25(Track)EG Risk 25/100SSVC: Track
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computedSeverity56% × 45%Exploitation0% × 40%Automatability0% × 15%Action: Routine — remediate on your standard cadence. - EPSS
- 4.2%
- KEV
- Not listed
Published
July 20, 2026
Last Modified
July 21, 2026
Advisory Details (1)
Auto-updated Jul 20, 2026WCOW cache mount source selector resolves NTFS junctions outside of cache root · Advisory · moby/buildkit · GitHub
https://github.com/moby/buildkit/security/advisories/GHSA-388v-wmr2-g2v2Vendor Advisories for CVE-2026-15788(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 8× in last 7d / 8× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-07-23 14:18 UTCEPSS rescore
- 2026-07-23 03:05 UTCEG score recompute
- 2026-07-22 23:30 UTCEG score recompute
- 2026-07-22 14:08 UTCEPSS rescore
- 2026-07-21 15:24 UTCEPSS rescore
- 2026-07-20 20:42 UTCEG score recompute
- 2026-07-20 19:57 UTCEG score recompute
- 2026-07-20 19:57 UTCMITRE cvelistV5first tracked
Related CVEs(same CWE)
Frequently asked(5)
What is CVE-2026-15788?
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Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2026-15788
Is Your Infrastructure Affected by CVE-2026-15788?
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