gcdRadar
archive/Patch now/AIR-2026-0258
closedclosed 7 Oct 2026Patch now2 Disclosed vulnerabilityAI

CVE-2026-103435: Time-of-check to time-of-use vulnerability in Claude Code sandbox

Claude Code

A TOCTOU gap in Claude Code permits attackers with workspace write access to use symlinks for writing output outside the project sandbox. Exploitation requires winning a race condition against the file write.

disclosed CVENo confirmed exploitation, so this record is tracked as a disclosed vulnerability and not counted as an incident. It moves into the counts if CISA or the vendor confirms exploitation. Why

CVSS
7.7
EPSS
<0.01 · top 84% · 2026-11-13
EPSS scores by FIRST
fix status
Fix status unknown
first report
7 Oct 2026
last update
7 Oct 2026
CVE ids
CVE-2026-103435other records

Timeline · 1

  1. 7 Oct 2026CVE-2026-103435: Claude Code validated that a target file path resided within the project working directory at permission-check time, but…

Sources · 1

Advisories and databases

  1. 2026-10-07
    CVE-2026-103435: Claude Code validated that a target file path resided within the project working directory at permission-check time, but…
    NVD · nvd.nist.gov/vuln/detail/CVE-2026-103435

Titles and links belong to their publishers. The summary above is written by gcdRadar in its own words; data is CC BY-SA 4.0.

Classification

lane
Patch now
AI role
Attack on AI
categories
Infrastructure vulnerability
severity
2 · Disclosed vulnerability
fix status
Fix status unknown
targets
Anthropic, Framework / tooling
owasp llm top 10
LLM03:2025 Supply Chain
mitre atlas
no technique for these categories
tags
toctousymlink
dates
happened 7 Oct 2026 · first reported 7 Oct 2026
origin
NVD
Vulnerability record from NVD / the GitHub Advisory Database. This product uses the NVD API but is not endorsed or certified by the NVD.
record
confidence 0.95 · created 2026-10-18 06:33Z · updated 2026-10-18 06:33Z

Lane, AI role, categories and severity come from the classifier; the OWASP and ATLAS rows are derived from the categories. How these are assigned

Copy a brief

This record as a short Markdown brief, for a ticket, a chat or a coding agent.

the brief as text
# CVE-2026-103435: Time-of-check to time-of-use vulnerability in Claude Code sandbox

https://gcdradar.vercel.app/incidents/cve-2026-103435-time-of-check-to-time-of-use-vulnerability-i · AIR-2026-0258 · closed 2026-10-07

- Lane: Patch now
- Severity: 2 (Disclosed vulnerability)
- Fix status: Fix status unknown
- First reported: 2026-10-07
- AI role: Attack on AI
- Products: Claude Code
- CVE ids: CVE-2026-103435
- CVSS: 7.7

## Summary

A TOCTOU gap in Claude Code permits attackers with workspace write access to use symlinks for writing output outside the project sandbox. Exploitation requires winning a race condition against the file write.

## What to do

No action recorded; read the sources below and the vendor's advisory.

## Latest updates

- 2026-10-07: CVE-2026-103435: Claude Code validated that a target file path resided within the project working directory at permission-check time, but… (https://nvd.nist.gov/vuln/detail/CVE-2026-103435)

## Sources

- 2026-10-07 NVD: CVE-2026-103435: Claude Code validated that a target file path resided within the project working directory at permission-check time, but… https://nvd.nist.gov/vuln/detail/CVE-2026-103435

Verify against the vendor's advisory before changing production. Data CC BY-SA 4.0, https://gcdradar.vercel.app.

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