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CVE-2026-33747· NVD / CVE Program· CNA GitHub_M

BuildKit vulnerable to malicious frontend causing file escape outside of storage root

Noroxi assessment

Priority: Monitor (action score 39/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.58% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: docker.io (Debian:13) 26.1.5+dfsg1-9+deb13u1; docker.io (Debian:14) 28.5.2+dfsg4-3; github.com/moby/buildkit (Go) 0.28.1.

Low priority for now. Upgrade to docker.io (Debian:13) 26.1.5+dfsg1-9+deb13u1; docker.io (Debian:14) 28.5.2+dfsg4-3; github.com/moby/buildkit (Go) 0.28.1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

BuildKit is a toolkit for converting source code to build artifacts in an efficient, expressive and repeatable manner. Prior to version 0.28.1, when using a custom BuildKit frontend, the frontend can craft an API message that causes files to be written outside of the BuildKit state directory for the execution context. The issue has been fixed in v0.28.1. The vulnerability requires using an untrusted BuildKit frontend set with `#syntax` or `--build-arg BUILDKIT_SYNTAX`. Using these options with a well-known frontend image like `docker/dockerfile` is not affected.

CriticalCVSS 9.8 · v3.1—No exploit Fix available
Published
Mar 26, 2026
Updated
Jun 17, 2026
EPSS
0.5% · 46th percentile

Report tools

JSON

Action score

39

Monitor

Low priority for now.

CVSS
39 / 40 · 9.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.5%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
9.8
CNA · GitHub_M
8.4
1.4 point gap

CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-33747

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
mobyprojectbuildkit

Using buildkit? Add it to your stack and be the first to know about CVEs like this one. (Docker)

Watch new CVEs for buildkit

When you'll hear from us

  • when a new CVE affecting this product is published
  • when a record in your stack enters KEV or gets exploit code

One daily email digest (06:00 UTC); connect a webhook for KEV listings and weaponized exploits instantly.

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Running WordPress? Scan your site free with WP Lens

  • Stack alerts: add the products and versions you run, get the new CVEs that affect them
  • Uptime monitoring: 1 site, instant email when it goes down
  • Add your domain: subdomains and takeover risk scanned every week (1 domain)
  • 10 scans an hour on the security tools (3 a day without an account), an API key and MCP
  • All your scans in one panel: findings, what changed in the last scan, a report per domain or per client (PDF, share link)
All free tools

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Free account, no card. Unfollow any time.

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Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • mobyproject buildkitbefore 0.28.1

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

  • moby buildkit

    • < 0.28.1affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12docker.iofrom 0—
Debian:13docker.iobefore 26.1.5+dfsg1-9+deb13u126.1.5+dfsg1-9+deb13u1
Debian:14docker.iobefore 28.5.2+dfsg4-328.5.2+dfsg4-3
Gogithub.com/moby/buildkitbefore 0.28.10.28.1
openSUSE:Leap 15.6govulncheck-vulndbbefore 0.0.20260402T184258-150000.1.158.10.0.20260402T184258-150000.1.158.1
openSUSE:Tumbleweedconftestbefore 0.67.1-2.10.67.1-2.1
openSUSE:Tumbleweeddocker-stablebefore 24.0.9_ce-18.124.0.9_ce-18.1
openSUSE:Tumbleweedtailscalebefore 1.96.4-1.11.96.4-1.1
openSUSE:Tumbleweedtrivybefore 0.70.0-1.10.70.0-1.1
SUSE:Linux Enterprise Server 12 SP5-LTSSdocker-stablebefore 24.0.9_ce-1.37.124.0.9_ce-1.37.1

Same product

mobyproject: all records

Other highest-scoring records for the same primary product.

  • CVE-2024-23653BuildKit interactive containers API does not validate entitlements check
    40Plan
  • CVE-2024-23652BuildKit possible host system access from mount stub cleaner
    37Monitor
  • CVE-2026-33748BuildKit Git URL subdir component can cause access to restricted files
    32Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2024-23650Jan 31, 2024 · BuildKit possible panic when incorrect parameters sent from frontend
    21Monitor
  • ← EarlierCVE-2024-23651Jan 31, 2024 · BuildKit possible race condition with accessing subpaths from cache mounts
    29Monitor
  • Later →CVE-2026-15788Jul 20, 2026 · WCOW cache mount source selector resolves NTFS junctions outside of cache root
    22Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
debian:docker.io26.1.5+dfsg1-9+deb13u1 · Debian:13Package registry (OSV)
Go:github.com/moby/buildkit0.28.1Package registry (OSV)
opensuse:conftest0.67.1-2.1 · openSUSE:TumbleweedPackage registry (OSV)
opensuse:docker-stable24.0.9_ce-18.1 · openSUSE:TumbleweedPackage registry (OSV)
opensuse:govulncheck-vulndb0.0.20260402T184258-150000.1.158.1 · openSUSE:Leap 15.6Package registry (OSV)
opensuse:tailscale1.96.4-1.1 · openSUSE:TumbleweedPackage registry (OSV)
opensuse:trivy0.70.0-1.1 · openSUSE:TumbleweedPackage registry (OSV)
suse:docker-stable24.0.9_ce-1.37.1 · SUSE:Linux Enterprise Server 12 SP5-LTSSPackage registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-337481 days apartBuildKit Git URL subdir component can cause access to restricted files
    32Monitor
  • CVE-2026-15789117 days apartMalicious client can bypass destination directory validation on local sources upload
    27Monitor
  • CVE-2026-15791117 days apartLLB file operation can be tricked to remove /tmp directory contents
    7Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-22 · Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

nvd-primary

Root cause

A user-supplied file name is joined with the allowed directory, but the result is never checked to confirm it is still inside that directory.

The bug in code

The whole CWE-22 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

ts
const file = path.join(ROOT, req.query.name);res.sendFile(file);

Fixed

ts
const file = path.resolve(ROOT, req.query.name);if (!file.startsWith(ROOT + path.sep)) {  return res.sendStatus(400);}res.sendFile(file);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (1 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records