{"items":[{"id":"NVI-00018467","kind":"vulnerability","title":"python-multipart: Quadratic-time querystring parsing with semicolon separators causes CPU denial of service","revision":1,"unknowns":["Customer inventory, deployment, reachability and exploitation have not been inspected."],"lifecycle":"active","identifiers":["GHSA-5rvq-cxj2-64vf","CVE-2026-53539"],"plain_summary":"GitHub lists this reviewed advisory for python-multipart. 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-2a192c043d1f9ffa62edcfbe6b328595"],"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":[{"kind":"CVSS","as_of":"2026-06-15T20:24:10.000Z","value":"7.5 high","meaning":"GitHub source severity; exploitability and local consequence require separate evidence.","source_id":"sr-2a192c043d1f9ffa62edcfbe6b328595"}],"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-2a192c043d1f9ffa62edcfbe6b328595","url":"https://github.com/advisories/GHSA-5rvq-cxj2-64vf","basis":"vendor_advisory","notes":"GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.","title":"GHSA-5rvq-cxj2-64vf","publisher":"GitHub Advisory Database","observed_at":"2026-11-06T07:20:20.042Z"}],"affected_context":[{"certainty":"source_listed","source_ids":["sr-2a192c043d1f9ffa62edcfbe6b328595"],"technology":"python-multipart","known_exclusions":[],"conditions_summary":"### Summary\n\nWhen parsing `application/x-www-form-urlencoded` bodies, `QuerystringParser` located the field separator with a two step lookup: it first scanned the entire remaining buffer for `&`, and only when no `&` existed anywhere ahead did it fall back to scanning for `;`. For a body that uses `;` as the separator and contains no `&`, every field iteration performed a full failed `&` scan over the entire remaining buffer before locating the nearby `;`. With N semicolon separated fields in a chunk of size B, this yields O(B^2) byte comparisons per chunk.\n\nAn attacker can submit a small crafted body of the form `a;a;a;...` and cause the parser to spend seconds of CPU per request. A handful of concurrent requests can exhaust worker processes.\n\n### Details\n\nIn `python_multipart/multipart.py`, both the `FIELD_NAME` and `FIELD_DATA` states located the next separator like this:\n\n```python\nsep_pos = data.find(b\"&\", i)\nif sep_pos == -1:\n    sep_pos = data.find(b\";\", i)\n```\n\n`data.find(b\"&\", i)` scans from `i` to the end of the buffer and returns `-1` only when there is no `&` anywhere in the remainder. For a `;` separated body with no `&`, this failed full buffer scan repeats once per f","public_affected_ranges":["< 0.0.30"]}],"null_published_at":"2026-11-07T07:07:39.839Z","source_updated_at":"2026-06-15T20:24:10.000Z","source_disclosed_at":"2026-06-15T20:24:09.000Z","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":"2026-11-06T07:20:20.042Z"}],"next_cursor":null,"snapshot_revision":"42594"}