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CVE-2026-103435

HIGH 7.7

Published 2026-10-07 · Last modified 2026-10-07

Claude Code validated that a target file path resided within the project working directory at permission-check time, but re-resolved the path at write time without repeating that validation. This time-of-check to time-of-use (TOCTOU) gap allowed an attacker who could write to the workspace to atomically replace a project file with a symlink, causing Claude Code to follow the symlink and write its output to an arbitrary file outside the project sandbox. Exploitation required the ability to win a race condition against the write operation and write access to the shared workspace, enabling a lower-privileged attacker to redirect benign edits to sensitive files (e.g., shell configuration) in a higher-privileged session. 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/c_h4ck_0 for reporting this issue.

ELEVATED IMPACT

Severe if exploited (CVSS 7.7), but no known exploitation and low modeled probability. Patch on a normal cadence.

Exploitation likelihood

0.3%chance of exploitation in 30 days · 16th percentile

○ In CISA KEV ○ Catalogued PoC

Impact if exploited

7.7CVSS 4.0 · HIGH

  • ConfidentialityHigh
  • IntegrityHigh
  • AvailabilityHigh

What an attacker needs

  • ✓Access: Reachable over the network — no local access needed
  • ✓Privileges: No account or privileges required
  • ⚠User interaction: Succeeds with passive user activity
  • ✓Complexity: No special conditions — reliably repeatable
  • ⚠Requirements: Specific conditions must be present

✓ lowers the bar for an attacker · ⚠ raises it

Proof of concept

No public PoC is currently catalogued.

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Data snapshot:

Affected

Vendors Anthropic

Products @Anthropic Ai/Claude Code

Weakness (CWE)

  • CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
  • CWE-61: UNIX Symbolic Link (Symlink) Following
  • CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

References and research data (JSON)

Vendor product assessments

  • devspaces/pluginregistry-rhel9 as a component of Red Hat OpenShift Dev Spaces · known affected

    Vendor assessment for this product only.

    pkg:oci/pluginregistry-rhel9@sha256:8d974db58d7be47a789854afc09a6aaae83dccf38bdbf1b4940a2830497004f4?repository_url=registry.redhat.io/devspaces/pluginregistry-rhel9

    • workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability. Upstream advises that users on standard Claude Code auto-update have already received the fix and that users performing manual updates should update to the latest version.
    • none available: Affected
    Red Hat · CVE-2026-103435 · Updated 2026-10-15T23:31:58+00:00

All CVSS metrics

  • HIGH 7.7 v4.0 · CNA Primary
    CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
  • HIGH 7.7 v4.0 · NVD Secondary
    CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/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

References

Advisories

Technical & other

Sources: NVD · CVE.org · EPSS