{"items":[{"id":"NVI-00018308","kind":"vulnerability","title":"CBORDecoder reuse can leak shareable values across decode calls","revision":1,"unknowns":["Customer inventory, deployment, reachability and exploitation have not been inspected."],"lifecycle":"active","identifiers":["GHSA-wcj4-jw5j-44wh","CVE-2025-68131"],"plain_summary":"GitHub lists this reviewed advisory for cbor2. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.","review_status":"source_listed","control_topics":[],"public_actions":[{"summary":"Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.","source_ids":["sr-0d9c540a5752138c9ce4a8c12b3dbb91"],"action_type":"investigate","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null}],"schema_version":"1.1.0","source_metrics":[],"why_it_matters":"Published affected context helps an owner decide what evidence to gather. This report has not examined your application.","related_sources":[{"id":"sr-0d9c540a5752138c9ce4a8c12b3dbb91","url":"https://github.com/advisories/GHSA-wcj4-jw5j-44wh","basis":"vendor_advisory","notes":"GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.","title":"GHSA-wcj4-jw5j-44wh","publisher":"GitHub Advisory Database","observed_at":"2026-11-07T00:53:06.181Z"}],"affected_context":[{"certainty":"source_listed","source_ids":["sr-0d9c540a5752138c9ce4a8c12b3dbb91"],"technology":"cbor2","known_exclusions":[],"conditions_summary":"### Summary\nWhen a CBORDecoder instance is reused across multiple decode operations, values marked with the shareable tag (28) persist in memory and can be accessed by subsequent CBOR messages using the sharedref tag (29). This allows an attacker-controlled message to read data from previously decoded messages if the decoder is reused across trust boundaries.\n\n### Details\nThe issue is in the decoder's handling of the shareables list, which stores values tagged with CBOR tag 28 (shareable) for later reference by tag 29 (sharedref).\n\nWhen decode_from_bytes() is called or when .fp is set to a new stream, the shareables list is not cleared. This allows references to persist across separate decode operations.\n\nThe issue exists in both the C extension and the pure Python decoder.\n\nIn the C extension (source/decoder.c), the _CBORDecoder_set_fp function (line ~202) updates the file pointer but does not reset the shareables state:\n\n```\n  static int\n  _CBORDecoder_set_fp(CBORDecoderObject *self, PyObject *value, void *closure)\n  {\n      // ... validation ...\n      tmp = self->read;\n      self->read = read;\n      Py_DECREF(tmp);\n      return 0;\n      // Missing: PyList_Clear(self->shareables)","public_affected_ranges":[">= 3.0.0, < 5.8.0"]}],"null_published_at":"2026-11-07T07:07:39.808Z","source_updated_at":"2026-06-05T14:17:48.000Z","source_disclosed_at":"2025-12-31T22:01:38.000Z","is_synthetic_fixture":false,"null_last_reviewed_at":null,"public_change_summary":"First indexed by Null; source disclosure date is shown separately.","null_first_observed_at":"2026-11-07T00:53:06.181Z"}],"next_cursor":null,"snapshot_revision":"42594"}