CVE-2026-81028 (GCVE-0-2026-81028)
Vulnerability from cvelistv5 – Published: 2026-08-26 15:44 – Updated: 2026-08-26 15:44
VLAI
EPSS
VEX
Title
ZLMediaKit downloadFile Root-Directory Confinement Bypass via Prefix Collision
Summary
ZLMediaKit confines the downloadFile API to a configured set of root directories with a prefix comparison that does not account for directory boundaries. The configuration loader in server/WebApi.cpp builds each root with File::absolutePath("", item, true); because the relative-path argument is empty that helper returns the value without a trailing separator. The handler then accepts a requested path when start_with(file_path, root) holds, so a sibling directory whose name merely begins with the configured root string satisfies the test and is served. The only other guard rejects a path containing two dots, which this requires none of. The equivalent confinement check for the ordinary static file server in src/Http/HttpFileManager.cpp computes its root with a non-empty second argument, which appends the separator before comparing, and so is not affected. The endpoint requires the configured API secret, so this grants no privilege beyond what that secret already implies, but it reads files outside the directory the operator confined it to, and the reference container runs the server as root.
Severity
4.9 (Medium)
CWE
- CWE-22 - Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Assigner
References
4 references
| URL | Tags |
|---|---|
| https://github.com/ZLMediaKit/ZLMediaKit | product |
| https://github.com/ZLMediaKit/ZLMediaKit/issues/4817 | issue-tracking |
| https://github.com/ZLMediaKit/ZLMediaKit/blob/fa3… | technical-description |
| https://www.vulncheck.com/advisories/zlmediakit-d… | third-party-advisory |
Impacted products
1 product
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| ZLMediaKit | ZLMediaKit |
Affected:
fa347d7dbe48dfdce525d3a0fdb92e576970ef9f
(git)
|
guessed |
Date Public
2026-08-26 00:00
{
"containers": {
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{
"collectionURL": "https://github.com/ZLMediaKit/ZLMediaKit",
"defaultStatus": "affected",
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"repo": "https://github.com/ZLMediaKit/ZLMediaKit",
"vendor": "ZLMediaKit",
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"type": "finder",
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}
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}
],
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"attackVector": "NETWORK",
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"exploitMaturity": "NOT_DEFINED",
"privilegesRequired": "HIGH",
"providerUrgency": "NOT_DEFINED",
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"userInteraction": "NONE",
"valueDensity": "NOT_DEFINED",
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"problemTypes": [
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"descriptions": [
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"description": "Improper Limitation of a Pathname to a Restricted Directory (\u0027Path Traversal\u0027)",
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"providerMetadata": {
"dateUpdated": "2026-08-26T15:44:57.303Z",
"orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
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},
"references": [
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"tags": [
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],
"url": "https://github.com/ZLMediaKit/ZLMediaKit"
},
{
"tags": [
"issue-tracking"
],
"url": "https://github.com/ZLMediaKit/ZLMediaKit/issues/4817"
},
{
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"technical-description"
],
"url": "https://github.com/ZLMediaKit/ZLMediaKit/blob/fa347d7dbe48dfdce525d3a0fdb92e576970ef9f/server/WebApi.cpp"
},
{
"name": "VulnCheck Advisory: ZLMediaKit downloadFile Root-Directory Confinement Bypass via Prefix Collision",
"tags": [
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],
"url": "https://www.vulncheck.com/advisories/zlmediakit-downloadfile-root-directory-confinement-bypass-via-prefix-collision"
}
],
"source": {
"discovery": "UNKNOWN"
},
"title": "ZLMediaKit downloadFile Root-Directory Confinement Bypass via Prefix Collision",
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"cveMetadata": {
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"cveId": "CVE-2026-81028",
"datePublished": "2026-08-26T15:44:57.303Z",
"dateReserved": "2026-08-26T15:23:05.351Z",
"dateUpdated": "2026-08-26T15:44:57.303Z",
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"vulnerability-lookup:meta": {
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"date": "2026-08-27",
"epss": "0.0035",
"percentile": "0.27775"
},
"nvd": "{\"cve\":{\"id\":\"CVE-2026-81028\",\"sourceIdentifier\":\"disclosure@vulncheck.com\",\"published\":\"2026-08-26T16:16:45.400\",\"lastModified\":\"2026-08-26T16:16:45.400\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"ZLMediaKit confines the downloadFile API to a configured set of root directories with a prefix comparison that does not account for directory boundaries. The configuration loader in server/WebApi.cpp builds each root with File::absolutePath(\\\"\\\", item, true); because the relative-path argument is empty that helper returns the value without a trailing separator. The handler then accepts a requested path when start_with(file_path, root) holds, so a sibling directory whose name merely begins with the configured root string satisfies the test and is served. The only other guard rejects a path containing two dots, which this requires none of. The equivalent confinement check for the ordinary static file server in src/Http/HttpFileManager.cpp computes its root with a non-empty second argument, which appends the separator before comparing, and so is not affected. The endpoint requires the configured API secret, so this grants no privilege beyond what that secret already implies, but it reads files outside the directory the operator confined it to, and the reference container runs the server as root.\"}],\"affected\":[{\"source\":\"disclosure@vulncheck.com\",\"affectedData\":[{\"vendor\":\"ZLMediaKit\",\"product\":\"ZLMediaKit\",\"defaultStatus\":\"affected\",\"collectionURL\":\"https://github.com/ZLMediaKit/ZLMediaKit\",\"repo\":\"https://github.com/ZLMediaKit/ZLMediaKit\",\"versions\":[{\"version\":\"fa347d7dbe48dfdce525d3a0fdb92e576970ef9f\",\"versionType\":\"git\",\"status\":\"affected\"}]}]}],\"metrics\":{\"cvssMetricV40\":[{\"source\":\"disclosure@vulncheck.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"4.0\",\"vectorString\":\"CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/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\",\"baseScore\":6.9,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"attackRequirements\":\"NONE\",\"privilegesRequired\":\"HIGH\",\"userInteraction\":\"NONE\",\"vulnConfidentialityImpact\":\"HIGH\",\"vulnIntegrityImpact\":\"NONE\",\"vulnAvailabilityImpact\":\"NONE\",\"subConfidentialityImpact\":\"NONE\",\"subIntegrityImpact\":\"NONE\",\"subAvailabilityImpact\":\"NONE\",\"exploitMaturity\":\"NOT_DEFINED\",\"confidentialityRequirement\":\"NOT_DEFINED\",\"integrityRequirement\":\"NOT_DEFINED\",\"availabilityRequirement\":\"NOT_DEFINED\",\"modifiedAttackVector\":\"NOT_DEFINED\",\"modifiedAttackComplexity\":\"NOT_DEFINED\",\"modifiedAttackRequirements\":\"NOT_DEFINED\",\"modifiedPrivilegesRequired\":\"NOT_DEFINED\",\"modifiedUserInteraction\":\"NOT_DEFINED\",\"modifiedVulnConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedVulnIntegrityImpact\":\"NOT_DEFINED\",\"modifiedVulnAvailabilityImpact\":\"NOT_DEFINED\",\"modifiedSubConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedSubIntegrityImpact\":\"NOT_DEFINED\",\"modifiedSubAvailabilityImpact\":\"NOT_DEFINED\",\"Safety\":\"NOT_DEFINED\",\"Automatable\":\"NOT_DEFINED\",\"Recovery\":\"NOT_DEFINED\",\"valueDensity\":\"NOT_DEFINED\",\"vulnerabilityResponseEffort\":\"NOT_DEFINED\",\"providerUrgency\":\"NOT_DEFINED\"}}],\"cvssMetricV31\":[{\"source\":\"disclosure@vulncheck.com\",\"type\":\"Primary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N\",\"baseScore\":4.9,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"HIGH\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"NONE\"},\"exploitabilityScore\":1.2,\"impactScore\":3.6}]},\"weaknesses\":[{\"source\":\"disclosure@vulncheck.com\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-22\"}]}],\"references\":[{\"url\":\"https://github.com/ZLMediaKit/ZLMediaKit\",\"source\":\"disclosure@vulncheck.com\"},{\"url\":\"https://github.com/ZLMediaKit/ZLMediaKit/blob/fa347d7dbe48dfdce525d3a0fdb92e576970ef9f/server/WebApi.cpp\",\"source\":\"disclosure@vulncheck.com\"},{\"url\":\"https://github.com/ZLMediaKit/ZLMediaKit/issues/4817\",\"source\":\"disclosure@vulncheck.com\"},{\"url\":\"https://www.vulncheck.com/advisories/zlmediakit-downloadfile-root-directory-confinement-bypass-via-prefix-collision\",\"source\":\"disclosure@vulncheck.com\"}]}}"
}
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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