CWE-515
Weakness AllowedCovert Storage Channel
Abstraction: Base · Status: Incomplete
A covert storage channel transfers information through the setting of bits by one program and the reading of those bits by another. What distinguishes this case from that of ordinary operation is that the bits are used to convey encoded information.
Covert storage channels occur when out-of-band data is stored in messages for the purpose of memory reuse. Covert channels are frequently classified as either storage or timing channels. Examples would include using a file intended to hold only audit information to convey user passwords--using the name of a file or perhaps status bits associated with it that can be read by all users to signal the contents of the file. Steganography - concealing information in such a manner that no one but the intended recipient knows of the existence of the message - is a good example of a covert storage channel.
Mapping guidance
This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.
Modes of introduction
Notes
Maintenance
As of CWE 4.9, members of the CWE Hardware SIG are working to improve CWE's coverage of transient execution weaknesses, which include issues related to Spectre, Meltdown, and other attacks that create or exploit covert channels. As a result of that work, this entry might change in CWE 4.10.
Content history
updated Time_of_Introduction
updated Common_Consequences, Relationships, Other_Notes, Taxonomy_Mappings
updated Description
updated Common_Consequences, Description
updated Other_Notes
updated Common_Consequences
updated Relationships
updated Relationships
updated Relationships
updated Maintenance_Notes
updated Relationships
updated Mapping_Notes
updated References
updated Applicable_Platforms, Weakness_Ordinalities
updated Description
2 vulnerabilities reference this CWE, most recent first.
CVE-2026-54316 (GCVE-0-2026-54316)
Vulnerability from cvelistv5 – Published: 2026-06-23 17:06 – Updated: 2026-06-23 17:37| URL | Tags |
|---|---|
| https://github.com/anthropics/claude-code/securit… | x_refsource_CONFIRM |
| Vendor | Product | Version | |
|---|---|---|---|
| anthropics | claude-code |
Affected:
>= 0.2.54, < 2.1.163
|
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"role": "CISA Coordinator",
"timestamp": "2026-06-23T17:37:32.464559Z",
"version": "2.0.3"
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"dateUpdated": "2026-06-23T17:37:38.468Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"product": "claude-code",
"vendor": "anthropics",
"versions": [
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"status": "affected",
"version": "\u003e= 0.2.54, \u003c 2.1.163"
}
]
}
],
"descriptions": [
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"lang": "en",
"value": "Claude Code is an agentic coding tool. From 0.2.54 until 2.1.163, because the hostname huggingface.co was pre-approved as a bare hostname for the WebFetch tool, any path on that domain\u2014including attacker-controlled model repositories\u2014was auto-approved without a permission prompt or being subject to --allowedTools restrictions. An attacker able to inject untrusted content into a Claude Code context could direct it to issue WebFetch requests against attacker-controlled repository files (e.g. /resolve/main/config.json), which HuggingFace counts as downloads server-side, creating a covert out-of-band channel for encoding and exfiltrating data Claude can access such as files, environment variables, or command output. Reliably exploiting this required the ability to add untrusted content into a Claude Code context window. This vulnerability is fixed in 2.1.163."
}
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"attackComplexity": "LOW",
"attackRequirements": "PRESENT",
"attackVector": "NETWORK",
"baseScore": 6,
"baseSeverity": "MEDIUM",
"privilegesRequired": "NONE",
"subAvailabilityImpact": "NONE",
"subConfidentialityImpact": "NONE",
"subIntegrityImpact": "NONE",
"userInteraction": "PASSIVE",
"vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N",
"version": "4.0",
"vulnAvailabilityImpact": "NONE",
"vulnConfidentialityImpact": "HIGH",
"vulnIntegrityImpact": "NONE"
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"descriptions": [
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"cweId": "CWE-200",
"description": "CWE-200: Exposure of Sensitive Information to an Unauthorized Actor",
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"references": [
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"name": "https://github.com/anthropics/claude-code/security/advisories/GHSA-fg94-h982-f3mm",
"tags": [
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"source": {
"advisory": "GHSA-fg94-h982-f3mm",
"discovery": "UNKNOWN"
},
"title": "Claude Code: Out-of-Band Data Exfiltration via Pre-Approved HuggingFace Domain in WebFetch"
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"datePublished": "2026-06-23T17:06:16.184Z",
"dateReserved": "2026-06-12T18:42:02.223Z",
"dateUpdated": "2026-06-23T17:37:38.468Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
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GHSA-FG94-H982-F3MM
Vulnerability from github – Published: 2026-06-17 18:06 – Updated: 2026-07-20 21:10Because the hostname huggingface.co was pre-approved as a bare hostname for the WebFetch tool, any path on that domain—including attacker-controlled model repositories—was auto-approved without a permission prompt or being subject to --allowedTools restrictions. An attacker able to inject untrusted content into a Claude Code context could direct it to issue WebFetch requests against attacker-controlled repository files (e.g. /resolve/main/config.json), which HuggingFace counts as downloads server-side, creating a covert out-of-band channel for encoding and exfiltrating data Claude can access such as files, environment variables, or command output. Reliably exploiting this required the ability to add untrusted content into a Claude Code context window. Users on standard Claude Code auto-update have received this fix already; users performing manual updates are advised to update to the latest version.
Thank you to hackerone.com/novee for reporting this issue.
{
"affected": [
{
"package": {
"ecosystem": "npm",
"name": "@anthropic-ai/claude-code"
},
"ranges": [
{
"events": [
{
"introduced": "0.2.54"
},
{
"fixed": "2.1.163"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-54316"
],
"database_specific": {
"cwe_ids": [
"CWE-183",
"CWE-200",
"CWE-515"
],
"github_reviewed": true,
"github_reviewed_at": "2026-06-17T18:06:06Z",
"nvd_published_at": "2026-06-23T18:18:08Z",
"severity": "MODERATE"
},
"details": "Because the hostname huggingface.co was pre-approved as a bare hostname for the WebFetch tool, any path on that domain\u2014including attacker-controlled model repositories\u2014was auto-approved without a permission prompt or being subject to --allowedTools restrictions. An attacker able to inject untrusted content into a Claude Code context could direct it to issue WebFetch requests against attacker-controlled repository files (e.g. /resolve/main/config.json), which HuggingFace counts as downloads server-side, creating a covert out-of-band channel for encoding and exfiltrating data Claude can access such as files, environment variables, or command output. Reliably exploiting this required the ability to add untrusted content into a Claude Code context window. Users on standard Claude Code auto-update have received this fix already; users performing manual updates are advised to update to the latest version.\n\nThank you to hackerone.com/novee for reporting this issue.",
"id": "GHSA-fg94-h982-f3mm",
"modified": "2026-07-20T21:10:30Z",
"published": "2026-06-17T18:06:06Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/anthropics/claude-code/security/advisories/GHSA-fg94-h982-f3mm"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-54316"
},
{
"type": "PACKAGE",
"url": "https://github.com/anthropics/claude-code"
}
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"schema_version": "1.4.0",
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"type": "CVSS_V3"
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"score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "Claude Code: Out-of-Band Data Exfiltration via Pre-Approved HuggingFace Domain in WebFetch"
}
Mitigation
Ensure that all reserved fields are set to zero before messages are sent and that no unnecessary information is included.
No CAPEC attack patterns related to this CWE.