EUVD-2026-81054
GHSA-2jmw-fcwx-7j6h
Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
-
AccessLocate exposed Kraken testfs tag endpoint
-
DeliverySend GET /tags/ with percent-encoded ../ segments
-
ExploitBypass unvalidated path join in pather.go
-
Executiontestfs process reads file outside storage root
-
ImpactExfiltrate sensitive file contents
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V5 - File Handling Path canonicalization, traversal prevention
MITRE ATT&CK
2 techniques across 2 tactics: Discovery, Collection The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Exploitation Conditions | Requires that the target run Kraken's testfs backend and expose the build-index tagserver /tags/{tag} endpoint to the attacker's network; no authentication, user interaction, or non-default flag beyond backend selection is needed on that path. The principal limiting factor is that testfs is a simple test/development filesystem server rather than the origin backends (e.g., S3/HDFS) typically used in production Kraken clusters, so environments not using testfs are not exposed. Disclosure is bounded to files readable by the testfs process account. |
| Impact | The CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N, score 8.7) describes an unauthenticated, network-reachable, low-complexity path traversal with High confidentiality impact and NO integrity or availability impact - this is a read-only arbitrary-file-disclosure bug, not RCE. All exploitation signals are quiet: not listed in CISA KEV, no EPSS score provided, and no public exploit code identified (references cover the GitHub issue #645, the source lines, and a VulnCheck advisory, but none is a weaponized PoC). The single most important nuance the raw score hides is that the flaw lives in Kraken's testfs backend (testfs/server.go), a simple test/development filesystem server rather than Kraken's typical production origin backends (S3/HDFS/etc.). Real-world risk is therefore materially lower than the 8.7 suggests: PR:N is technically correct, but exploitation is conditioned on an operator running the testfs backend and exposing its tag endpoint to attackers. Net: a genuine unauthenticated file-read primitive that warrants patching, but closer to a targeted/limited-deployment concern than a broad internet-wide threat. |
| Exploit ScenarioDerived | An attacker who can reach a Kraken build-index tagserver running the testfs backend sends a GET to /tags/{tag} where {tag} contains percent-encoded ../ sequences. Because namepath/pather.go does not validate the tag before joining it to the storage root, the request resolves outside the configured directory and returns arbitrary files readable by the testfs process (e.g., configs, credentials, keys). No authentication or user interaction is required, though no public exploit code has been published - only the vulnerability report and advisory. |
Get an e-mail when this CVE is exploited, patched or re-scored. Free account.
Alert meAnalysisAIv1 – Sep 16, 2026
Unauthenticated path traversal in Uber Kraken through 0.1.29 allows remote attackers to read files outside the configured storage root via the /tags/{tag} endpoint when the testfs backend and build-index tagserver are exposed. Percent-encoded parent-directory segments in the tag parameter bypass path validation and disclose files readable by the testfs process account, yielding high confidentiality impact with no integrity or availability effect. No public exploit identified at time of analysis.
RemediationAI
No vendor-released patch identified at time of analysis; affected releases are through 0.1.29, and the referenced GitHub issue 645 plus repository and source links should be monitored for a fixed release. The most effective immediate mitigation is to not run the testfs backend in production and to block untrusted network access to the build-index tagserver /tags/{tag} endpoint, because the vulnerability requires that endpoint to be reachable and that backend to be active; this may break test/development or registry tag workflows that rely on testfs. If the endpoint must remain reachable, place it behind network ACLs or a reverse proxy that rejects percent-encoded parent-directory sequences and restricts access to trusted registry components, accepting that proxy normalization can be bypassed if not carefully implemented. Run the testfs process under a low-privileged account with read access only to necessary storage to limit file disclosure, though this reduces rather than eliminates impact. Consult https://www.vulncheck.com/advisories/uber-kraken-through-0.1.29-path-traversal-via-tag-parameter and https://github.com/uber/kraken/issues/645 for updates.
Affected VersionsENISA
Affected Packages
Source: OSV (Open Source Vulnerabilities)
Affects your stack
Affects 1 package in euvd
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
Uber Kraken is a P2P Docker registry; the issue is CWE-22 path traversal in the build-index tagserver's /tags/{tag} route, where the tag parameter is passed into namepath/pather logic and then to the testfs backend's file operations. The referenced code locations (pather.go lines 78-84, testfs/server.go lines 165-173, tagserver/server.go lines 128-129) indicate that path construction and backend file handling do not reject parent-directory sequences, so percent-encoded segments survive into the filesystem path and escape the configured storage root. The CPE cpe:2.3:a:uber:kraken:*:*:*:*:*:*:*:* covers Kraken generally under this advisory, with the practical affected population limited to testfs-based test/development deployments; the flaw is read-only information disclosure, not code execution.
Know when Kraken gets its next vulnerability
- Watch products and get an email when something new is published
- Check this CVE against your own stack and servers
- Exploit and PoC references, threat intelligence from 22 sources
No credit card · 7-day full trial
Severity by source
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
Unauthenticated network path traversal (PR:N/AC:L) yielding arbitrary file read for High confidentiality; no write or availability impact so I:N/A:N, and no scope change.
Primary rating from Vendor (VulnCheck).
CVSS VectorVendor: VulnCheck
DescriptionCVE.org
Uber Kraken through 0.1.29 fails to validate the tag parameter in the /tags/{tag} endpoint, allowing unauthenticated attackers to traverse outside the configured storage root. Attackers can use percent-encoded parent-directory segments in the tag parameter to read arbitrary files accessible to the testfs backend process.
Technical POC Analysis
Evidence basis: the supplied material is a CTI summary gist plus the advisory metadata in the task prompt (CVE ID, CVSS, CWE, affected versions, endpoint, backend names).
Full technical POC analysis - root cause, step-by-step exploitation and patch breakdown - is part of the Pro and Business plans.
Latest POC
1 PoC candidate from github (unverified)
Sign in to open the public PoC links collected for this CVE.
Executive ViewAI
A path-traversal vulnerability in Uber Kraken (versions through 0.1.29) lets attackers read files outside the intended storage root on deployments where the testfs backend and build-index tagserver are exposed, creating a direct confidentiality risk for any sensitive data those processes can reach. Because no vendor patch is currently available, affected teams are reliant on containment rather than remediation. Leadership should care if Kraken is used to serve container/artifact storage, since exposed configuration, credentials, or proprietary build content could be disclosed without any sign of data tampering or service disruption.
No vendor-released patch identified at time of analysis. Interim mitigations: remove external exposure of the /tags/{tag} endpoint and the testfs/build-index tagserver; block percent-encoded traversal payloads at the WAF or reverse proxy; run the testfs process account with least privilege and no access to sensitive files; log and monitor tag endpoint requests for traversal attempts.
Threat Intelligence Overview
NVD
CVE.org
EPSS
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Path traversal exploits occur when applications use user-controlled input to construct file system paths without proper validation.
Cross-Site Request Forgery (CSRF) vulnerability in Kraken.io Image Optimizer plugin <= 2.6.5 at WordPress. Rated high se
The Kraken.io Image Optimizer plugin for WordPress is vulnerable to authorization bypass due to a missing capability che
Exploit-DB