{"id":"CVE-2026-104851","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-104851","generatedAt":"2026-10-28T03:26:05.818Z","title":"A document supplied inline or fetched from an attacker-controlled URL can provide template expressions that execute Python code when the reference filesystem is opened, including through consumers such as xarray, before referenced data is read.","description":"fsspec is a specification and Python implementation framework for filesystem interfaces. From 0.9.0 until 2026.6.0, fsspec.implementations.reference.ReferenceFileSystem evaluates fields from Kerchunk reference JSON documents through unrestricted jinja2.Template(...).render(...) calls in _process_references1._render_jinja, _process_templates, and _process_gen in fsspec/implementations/reference.py. A document supplied inline or fetched from an attacker-controlled URL can provide template expressions that execute Python code when the reference filesystem is opened, including through consumers such as xarray, before referenced data is read. The _process_gen path is reached whenever a document includes a gen array, while the other paths depend on template-related options and values. This issue is fixed in version 2026.6.0.","published":"2026-10-02T17:17:04.000Z","lastModified":"2026-10-05T20:17:09.000Z","status":"Deferred","sourceIdentifier":"security-advisories@github.com","cvss":{"version":"3.1","score":8.8,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H"},"cwe":["CWE-94","CWE-1336"],"affected":[],"epss":{"score":0.00475,"percentile":0.40776,"date":"2026-10-26","history":[{"date":"2026-10-03","score":0.00317,"percentile":0.22438}]},"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 (0.47%). 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":"2026-10-02T17:17:04.000Z","detail":{"score":"8.8","severity":"HIGH","publishedAt":"2026-10-02T17:17:03.763Z"},"summary":"New CVE, high severity (CVSS 8.8)."}],"references":[{"url":"https://github.com/fsspec/filesystem_spec/commit/86438783f93b1398ef245b92f0e6063b445b611c","source":"security-advisories@github.com"},{"url":"https://github.com/fsspec/filesystem_spec/commit/a1c16ab3f07f354aa371c38f7b1b07ea7fd4c5c8","source":"security-advisories@github.com"},{"url":"https://github.com/fsspec/filesystem_spec/pull/2029","source":"security-advisories@github.com"},{"url":"https://github.com/fsspec/filesystem_spec/pull/2039","source":"security-advisories@github.com"},{"url":"https://github.com/fsspec/filesystem_spec/releases/tag/2026.6.0","source":"security-advisories@github.com"},{"url":"https://github.com/fsspec/filesystem_spec/security/advisories/GHSA-27vj-qcqg-25rc","source":"security-advisories@github.com"},{"url":"https://github.com/fsspec/filesystem_spec/security/advisories/GHSA-27vj-qcqg-25rc","source":"134c704f-9b21-4f2e-91b3-4a467353bcc0"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-104851","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."}