{"items":[{"id":"NVI-00013037","kind":"vulnerability","title":"fast-uri vulnerable to mailto header injection via percent-encoded field-name desynchronization","revision":1,"unknowns":["Customer inventory, deployment, reachability and exploitation have not been inspected."],"lifecycle":"active","identifiers":["GHSA-jvvf-x445-j334","CVE-2026-86818"],"plain_summary":"GitHub lists this reviewed advisory for fast-uri. 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-4426394b82f64b45ba4930a81271094a"],"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":"2026-09-29T23:51:17.000Z","value":"4.8 medium","meaning":"GitHub source severity; exploitability and local consequence require separate evidence.","source_id":"sr-4426394b82f64b45ba4930a81271094a"}],"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-4426394b82f64b45ba4930a81271094a","url":"https://github.com/advisories/GHSA-jvvf-x445-j334","basis":"vendor_advisory","notes":"GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.","title":"GHSA-jvvf-x445-j334","publisher":"GitHub Advisory Database","observed_at":"2026-11-01T07:24:25.558Z"}],"affected_context":[{"certainty":"source_listed","source_ids":["sr-4426394b82f64b45ba4930a81271094a"],"technology":"fast-uri","known_exclusions":[],"conditions_summary":"### Impact\n\n`fast-uri`'s `mailto` scheme parser compares each query field name to the reserved names (`to`, `subject`, `body`) while the name is still percent-encoded, and only percent-decodes it when storing it as a generic header. On serialize, the decoded name is re-emitted, so a field name such as `%74o` (percent-encoded `to`) is not recognized as a recipient at parse time (`parse().to` shows only the legitimate recipient) but materializes as a literal `to=` field after `serialize()`, and reparsing then treats it as a recipient. The same technique smuggles `subject` and `body` through `%73ubject` and `%62ody`.\n\nAn application that parses an untrusted mailto URI, makes a display, allowlist, or logging decision on `parse().to`, then re-serializes the result and passes the serialized string to a mail client or an outbound send path can gain an attacker-chosen recipient, subject, or body that was not visible when the recipient list was checked. A scanner inspecting the raw input for an extra `to=` sees nothing, because the injected field appears only after `fast-uri` serializes.\n\n### Patches\n\nUpgrade to `fast-uri` 4.1.5.\n\n### Workarounds\n\nPercent-decode and compare mailto field nam","public_affected_ranges":[">= 4.1.3, < 4.1.5"]}],"null_published_at":"2026-11-01T07:29:12.911Z","source_updated_at":"2026-09-29T23:51:17.000Z","source_disclosed_at":"2026-09-29T23:51:16.000Z","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":"2026-11-01T07:24:25.558Z"}],"next_cursor":null,"snapshot_revision":"42594"}