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Fencer Vulns
high 7.5

CVE-2026-15788 json

WCOW cache mount source selector resolves NTFS junctions outside of cache root

published 2026-07-20 3 mo ago modified 2026-10-24 15 d ago also EUVD-2026-46074

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 35%
public exploits
0
none known

Summary

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.

Patch / fix

  • moby BuildKit 0.31.2
  • buildah hummingbird 1 1.45.0-2.hum1
  • trivy hummingbird 1 0.72.0-0.1.2.hum1
  • podman hummingbird 1 6.0.2-2.1.hum1
  • podmansh hummingbird 1 6.0.2-2.1.hum1
  • podman-tests hummingbird 1 6.0.2-2.1.hum1
  • podman-docker hummingbird 1 6.0.2-2.1.hum1
  • podman-remote hummingbird 1 6.0.2-2.1.hum1
  • podman-machine hummingbird 1 6.0.2-2.1.hum1

red hat advisories RHSA-2026:51065RHSA-2026:46988RHSA-2026:44152RHSA-2026:43122

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-15788 updated cvss 6.3

github.com/moby/buildkit: BuildKit: Information Disclosure via Improper Handling of NTFS Directory Junctions

  • Red Hat Hardened Images buildah 1.45.0-2.hum1, podman 6.0.2-2.1.hum1, buildah 1.44.0-3.2.hum1, podmansh 6.0.2-2.1.hum1, trivy 0.72.0-0.1.2.hum1, podman-tests 6.0.2-2.1.hum1, +4 more
    fixed: vendor fix RHSA-2026:43122

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
3 mo ago

Exploit prediction

0.41% chance of exploitation in the next 30 days, higher than 35% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 5.6 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
CNA 4.0 5.6 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/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
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Affected products

  • moby BuildKit

Classification

Weakness
  • CWE-59 Improper Link Resolution Before File Access

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.