{"id":"CVE-2026-103435","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-103435","generatedAt":"2026-10-27T23:59:19.264Z","title":"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…","description":"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.\n\nUsers 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/c_h4ck_0 for reporting this issue.","published":"2026-10-07T13:17:17.000Z","lastModified":"2026-10-07T15:16:57.000Z","status":"Awaiting Analysis","sourceIdentifier":"98a01053-8a31-4f6d-9aa9-252be161adc6","cvss":{"version":"4.0","score":7.7,"severity":"HIGH","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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M"},"cwe":["CWE-22","CWE-61","CWE-367"],"affected":[],"epss":{"score":0.00251,"percentile":0.1632,"date":"2026-10-26","history":[{"date":"2026-10-08","score":0.00251,"percentile":0.15086}]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (0.25%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[{"kind":"new","label":"New CVE","at":"2026-10-07T13:17:17.000Z","detail":{"score":"7.7","severity":"HIGH","publishedAt":"2026-10-07T13:17:16.690Z"},"summary":"New CVE, high severity (CVSS 7.7)."}],"references":[{"url":"https://github.com/anthropics/claude-code/security/advisories/GHSA-5j29-h97v-84ch","source":"98a01053-8a31-4f6d-9aa9-252be161adc6"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-103435","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}