CVE-2026-54316
criticalpriority · attend · 46EPSS 0.005 · 43 %ileexploit · PoCEUUSEPSS · scored 2026-10-23
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—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. This vulnerability is fixed in 2.1.163.
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–critical · 5.4–9.1
ssvc
A stakeholder decision — act, attend, or track — from exploitation and impact.
weaknesses
The CWE weakness classes this flaw belongs to.
exploits (1)
Public proof-of-concept and weaponised exploit code.
affected products (3)
Products and version ranges known to be affected.
advisories (1)
Vendor and ecosystem advisories describing this.
- GHSA-fg94-h982-f3mmClaude Code: Out-of-Band Data Exfiltration via Pre-Approved HuggingFace Domain in WebFetch2026-06-17ghsa · osvUS
Because 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.
also known as (3)
Other names and identifiers for this entity.
sources
Which sources assert this record, and when.
references (3)
External citations — patches, advisories, analysis.
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