CVE-2026-33747 | BuildKit vulnerable to malicious frontend causing file escape outside of storage root

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.

Published: 2026-03-27 Last update: 2026-04-01 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-33747 is rated Low Risk (39.8/100): CVSS High severity, with low exploitation likelihood (EPSS 0.06%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-33747

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-04-02 0.01% 0.06% +0.05%
2 2026-03-27 — 0.01% —

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-33747

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
8.4 3.1 HIGH
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.5 5.9 [email protected]
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]

Weakness enumeration for CVE-2026-33747

GitHub Security Advisory for CVE-2026-33747

GHSA-4c29-8rgm-jvjj · Severity: high · Ecosystem: go — BuildKit's Malicious frontend can cause file escape outside of storage root

OS Trackers for CVE-2026-33747

vendor priority summary link
alpine — CVE-2026-33747: 2 source package rows (buildkit, docker); 31 state rows across 2 repos (3.23-community, edge-community); fixed 1, open 30. https://security.alpinelinux.org/vuln/CVE-2026-33747
debian not yet assigned CVE-2026-33747 not yet assigned priority: Debian including 1 source packages (docker.io), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): open 5. https://security-tracker.debian.org/tracker/CVE-2026-33747
redhat medium — https://access.redhat.com/security/cve/CVE-2026-33747
suse high CVE-2026-33747 severity important: SUSE including 17 source package names (buildah, conftest-0.67.1-2.1, …), 142 product×package rows across 24 product lines (SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS, SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS, … (24 product lines)): Known Not Affected 134, Fixed 8. https://www.suse.com/security/cve/CVE-2026-33747/
ubuntu medium CVE-2026-33747 medium priority: Ubuntu including 2 source packages (docker.io, docker.io-app), 14 status rows across 8 suites (bionic, focal, jammy, noble, questing, resolute, upstream, xenial): needed 8, released 4, needs-triage 2. https://ubuntu.com/security/CVE-2026-33747

Affected software / configurations for CVE-2026-33747

Vendor Product Version Raw CPE
mobyproject buildkit < 0.28.1 cpe:2.3:a:mobyproject:buildkit:*:*:*:*:*:*:*:*

References for CVE-2026-33747

cvelogic Threat Intelligence