---
title: "CVE-2026-54316: Claude Code: Out-of-Band Data Exfiltration via Pre-Approved HuggingFace Domain in WebFetch"
url: https://erroneo.us/security/cve/CVE-2026-54316/
description: "CVE-2026-54316 (anthropics claude-code): Claude Code is an agentic coding tool. From 0.2.54 until 2.1.163, because the hostname huggingface.co was…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-06-23
date_modified: 2026-10-21
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-54316"
kev: false
cvss: 6
epss: 0.0052
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-54316: Claude Code: Out-of-Band Data Exfiltration via Pre-Approved HuggingFace Domain in WebFetch

**Signal:** Normal patch cycle. No exploitation signal; fix it in your next routine update if you are affected. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 0.5% , percentile 43: FIRST’s model estimates a 0.5% chance of exploitation activity in the next 30 days, higher than 43% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Editorial verdict: Check exposure. Gemini CLI and Claude Code Flaws Expose CI Secrets — If an AI coding agent runs in your CI on content outsiders can write (issues, PRs, comments), check versions and workflow permissions this week; laptop users on auto-update already have the fixes.

## What it is

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.

## Affected products (CVE record)

- anthropics claude-code: >= 0.2.54, < 2.1.163

## Severity

- GitHub_M CVSS 4.0: 6 `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`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none , automatable no , technical impact partial .
- FIRST EPSS (model of 2026-10-21): 0.52% probability of exploitation activity in the next 30 days; percentile 43.

## Sources

- [CVE.org record CVE-2026-54316](https://www.cve.org/CVERecord?id=CVE-2026-54316)
- [NVD entry CVE-2026-54316](https://nvd.nist.gov/vuln/detail/CVE-2026-54316)
- [github.com](https://github.com/anthropics/claude-code/security/advisories/GHSA-fg94-h982-f3mm)

---
Source page: https://erroneo.us/security/cve/CVE-2026-54316/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt