{"id":"CVE-2026-49114","state":"PUBLISHED","title":"ONNX symlink-following and path-traversal arbitrary file write","description":"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. 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.","publishedAt":"2026-08-21T16:10:56.241Z","updatedAt":"2026-08-21T16:43:10.933Z","severity":{"score":6.8,"label":"Medium","version":"4.0","vector":"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N","source":"cisa-cg"},"assigner":"cisa-cg","products":["ONNX ONNX"],"affected":[{"vendor":"ONNX","product":"ONNX","defaultStatus":"unknown","versions":[{"version":"0","status":"affected","lessThan":"1.21.0","versionType":"custom"},{"version":"1.21.0","status":"unaffected"}]}],"references":["https://github.com/onnx/onnx/security/advisories/GHSA-q56x-g2fj-4rj6","https://raw.githubusercontent.com/cisagov/CSAF/develop/csaf_files/IT/white/2026/va-26-233-01.json","https://www.cve.org/CVERecord?id=CVE-2026-49114"],"weaknesses":["CWE-367","CWE-22","CWE-59"],"ingestedAt":"2026-10-29T20:12:07.131Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/49xxx/CVE-2026-49114.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-49114","state":"PUBLISHED","datePublished":"2026-08-21T16:10:56.241Z","dateUpdated":"2026-08-21T16:43:10.933Z","assignerShortName":"cisa-cg","assignerOrgId":"9119a7d8-5eab-497f-8521-727c672e3725","dateReserved":"2026-05-27T16:19:04.848Z"},"containers":{"cna":{"title":"ONNX symlink-following and path-traversal arbitrary file write","descriptions":[{"lang":"en","value":"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. 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."}],"affected":[{"vendor":"ONNX","product":"ONNX","defaultStatus":"unknown","versions":[{"version":"0","status":"affected","lessThan":"1.21.0","versionType":"custom"},{"version":"1.21.0","status":"unaffected"}]}],"references":[{"url":"https://github.com/onnx/onnx/security/advisories/GHSA-q56x-g2fj-4rj6","name":"url","tags":["vendor-advisory","exploit"]},{"url":"https://raw.githubusercontent.com/cisagov/CSAF/develop/csaf_files/IT/white/2026/va-26-233-01.json","name":"url","tags":["third-party-advisory"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-49114","name":"url","tags":["vdb-entry"]}],"metrics":[{"cvssV3_1":{"scope":"UNCHANGED","version":"3.1","baseScore":7.1,"attackVector":"LOCAL","baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H","integrityImpact":"HIGH","userInteraction":"REQUIRED","attackComplexity":"LOW","availabilityImpact":"HIGH","privilegesRequired":"NONE","confidentialityImpact":"NONE"}},{"cvssV4_0":{"version":"4.0","baseScore":6.8,"attackVector":"LOCAL","baseSeverity":"MEDIUM","vectorString":"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N","userInteraction":"ACTIVE","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"NONE","subIntegrityImpact":"NONE","vulnIntegrityImpact":"HIGH","subAvailabilityImpact":"NONE","vulnAvailabilityImpact":"HIGH","subConfidentialityImpact":"NONE","vulnConfidentialityImpact":"NONE"}},{"other":{"type":"ssvc","content":{"timestamp":"2026-05-27T16:00:11.944488Z","id":"CVE-2026-49114","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-367","description":"CWE-367 Time-of-check Time-of-use (TOCTOU) Race Condition","lang":"en","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-22","description":"CWE-22 Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')","lang":"en","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-59","description":"CWE-59 Improper Link Resolution Before File Access ('Link Following')","lang":"en","type":"CWE"}]}],"providerMetadata":{"shortName":"cisa-cg","orgId":"9119a7d8-5eab-497f-8521-727c672e3725","dateUpdated":"2026-08-21T16:10:56.241Z"},"credits":[{"value":"tsigouris007","lang":"en"},{"value":"kpatsakis","lang":"en"}],"datePublic":"2026-03-31T00:00:00.000Z"},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-08-21T16:42:42.598941Z","id":"CVE-2026-49114","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-08-21T16:43:10.933Z"}}]}}}