{"id":"CVE-2026-49114","title":"In ONNX before 1.21.0, the 'save_external_data' function builds the external-data file path from the model's external_data location field and opens it for writing without 'O_NOFOLLOW/O_EXCL', after a non-atomic 'os.path.isfile()' check","summary":"In ONNX before 1.21.0, the 'save_external_data' function builds the external-data file path from the model's external_data location field and opens it for writing without 'O_NOFOLLOW/O_EXCL', after a non-atomic 'os.path.isfile()' check. …","severity":"high","cvss":7.1,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H","cwe":["CWE-22","CWE-59","CWE-367"],"vendor":"linuxfoundation","product":"onnx","affected":["onnx < 1.21.0"],"patched":["onnx 1.21.0"],"published":"2026-08-21","updated":"2026-09-16","sourceUpdated":"2026-09-16T13:55:10.540","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-49114","references":[{"url":"https://github.com/onnx/onnx/security/advisories/GHSA-q56x-g2fj-4rj6","label":"9119a7d8-5eab-497f-8521-727c672e3725"},{"url":"https://raw.githubusercontent.com/cisagov/CSAF/develop/csaf_files/IT/white/2026/va-26-233-01.json","label":"9119a7d8-5eab-497f-8521-727c672e3725"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-49114","label":"9119a7d8-5eab-497f-8521-727c672e3725"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-49114"},{"url":"https://github.com/onnx/onnx"},{"url":"https://pypi.org/project/onnx"},{"url":"https://github.com/advisories/GHSA-q56x-g2fj-4rj6"}],"tags":["nvd","osv","pip","ghsa"],"epss":0.00159,"epssPercentile":0.05526,"aliases":["GHSA-q56x-g2fj-4rj6","PYSEC-2026-3876"],"ecosystem":"pip","ingestedAt":"2026-08-22T19:24:27.429Z","slug":"CVE-2026-49114","body":"## Overview\n\nIn ONNX before 1.21.0, the 'save_external_data' function builds the external-data file path from the model's external_data location field and opens it for writing without 'O_NOFOLLOW/O_EXCL', after a non-atomic 'os.path.isfile()' check. A local attacker with write access to the directory where a victim serializes external data can deterministically pre-plant a symlink that is being followed, causing the victim's write to append to any file the victim can write, e.g. ~/.ssh/authorized_keys, cron files, or application configs. Fixed in 1.21.0.\n\n## Affected\n\n- `onnx < 1.21.0`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `onnx 1.21.0`\n\n## Package advisory (CVE-2026-49114)\n\nAffected packages:\n\n- `onnx < 1.21.0`\n\nPatched in:\n\n- `onnx 1.21.0`\n\nSource: https://osv.dev/vulnerability/GHSA-q56x-g2fj-4rj6","depth":"twilight","depthScore":39,"depthScoreParts":{"impact":39.1,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}