{"items":[{"id":"NVI-00017798","kind":"vulnerability","title":"`lxml_html_clean.Cleaner` does not strip `javascript:` URLs from namespaced URL attributes","revision":1,"unknowns":["Customer inventory, deployment, reachability and exploitation have not been inspected."],"lifecycle":"active","identifiers":["GHSA-4jhm-jv67-739f","CVE-2026-49825"],"plain_summary":"GitHub lists this reviewed advisory for lxml_html_clean. 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-6887ef0f93d028fa2c1e5277fb92021b"],"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":"2026-07-08T20:23:23.000Z","value":"8.2 high","meaning":"GitHub source severity; exploitability and local consequence require separate evidence.","source_id":"sr-6887ef0f93d028fa2c1e5277fb92021b"}],"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-6887ef0f93d028fa2c1e5277fb92021b","url":"https://github.com/advisories/GHSA-4jhm-jv67-739f","basis":"vendor_advisory","notes":"GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.","title":"GHSA-4jhm-jv67-739f","publisher":"GitHub Advisory Database","observed_at":"2026-11-04T23:34:51.634Z"}],"affected_context":[{"certainty":"source_listed","source_ids":["sr-6887ef0f93d028fa2c1e5277fb92021b"],"technology":"lxml_html_clean","known_exclusions":[],"conditions_summary":"# `lxml_html_clean.Cleaner` does not strip `javascript:` URLs from namespaced URL attributes (`xlink:href`)\n\n**Reporter:** Guillem Lefait  · **Date:** 2026-05-10\n**Affected:** `lxml` ≤ 6.1.0 and `lxml_html_clean` ≤ 0.4.4 (latest stable)\n**Confirmed against:** lxml 6.1.0 + lxml_html_clean 0.4.4 on Python 3.13.5, 3.14.4, and 3.15.0a8 (libxml2 2.14.6 / 2.9.14 — bug is in pure-Python sanitizer logic, independent of the libxml2 backend)\n**Root-cause class:** same as CVE-2021-28957 (`formaction` missing from `link_attrs`)\n\n## Summary\n\n`Cleaner` filters URL schemes (`javascript:`, `vbscript:`, …) by walking links via `rewrite_links()`, which delegates to `iterlinks()`, which only yields attributes named in `lxml.html.defs.link_attrs`. That allow-list contains no prefixed names (`xlink:href`) and no `srcset`. As a result, when `Cleaner` is configured with `safe_attrs_only=False` — a documented option for callers that want lenient attribute handling but still expect URL-scheme scrubbing — `` survives sanitization untouched, and any browser that follows the SVG-anchor specification will execute the JavaScript when the rendered link is clicked.","public_affected_ranges":["< 0.4.5"]}],"null_published_at":"2026-11-05T19:10:21.469Z","source_updated_at":"2026-07-08T20:23:23.000Z","source_disclosed_at":"2026-07-08T20:23:22.000Z","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":"2026-11-04T23:34:51.634Z"}],"next_cursor":null,"snapshot_revision":"42594"}