{"items":[{"id":"NVI-00018436","kind":"vulnerability","title":"CryptPad has a Sanitizer Bypass in Diffmarked.js that Allows Arbitrary HTML Injection and Potential XSS","revision":1,"unknowns":["Customer inventory, deployment, reachability and exploitation have not been inspected."],"lifecycle":"active","identifiers":["GHSA-g2g4-47gv-p72v","CVE-2026-26028"],"plain_summary":"GitHub lists this reviewed advisory for cryptpad. 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-23b3c3a68ac8aa5331fa558a691b9545"],"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":"2026-05-26T19:05:11.000Z","value":"6.1 medium","meaning":"GitHub source severity; exploitability and local consequence require separate evidence.","source_id":"sr-23b3c3a68ac8aa5331fa558a691b9545"}],"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-23b3c3a68ac8aa5331fa558a691b9545","url":"https://github.com/advisories/GHSA-g2g4-47gv-p72v","basis":"vendor_advisory","notes":"GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.","title":"GHSA-g2g4-47gv-p72v","publisher":"GitHub Advisory Database","observed_at":"2026-11-07T00:53:22.747Z"}],"affected_context":[{"certainty":"source_listed","source_ids":["sr-23b3c3a68ac8aa5331fa558a691b9545"],"technology":"cryptpad","known_exclusions":[],"conditions_summary":"### Summary\nCryptPad’s HTML sanitizer in Diffmarked.js can be bypassed due to incomplete filtering of restricted tags.\nBecause the sanitizer only validates the src attribute of `` ``, and `` elements,  and does not restrict other attributes, an attacker can inject arbitrary HTML through srcdoc. This completely defeats CryptPad’s intended bounce sandboxing and allows link injection or other interactive content inside user-controlled documents.\n\n### Details\nThe sanitizer defines forbidden and restricted tags but treats  as “restricted” instead of “forbidden”:\n\nhttps://github.com/cryptpad/cryptpad/blob/0dd3c1f53d56dffb06651b86ead6b9b387920173/www/common/diffMarked.js#L403-L407\nThe actual enforcement only checks the src attribute, nothing else:\n\nhttps://github.com/cryptpad/cryptpad/blob/0dd3c1f53d56dffb06651b86ead6b9b387920173/www/common/diffMarked.js#L445-L449\n\nBecause only src is validated, adding a benign blob: src but malicious srcdoc results in unrestricted rendering.\n### PoC\n\nAn attacker can embed arbitrary HTML, including clickable external links, images, or interactive content, completely bypassing CryptPad’s bounce mechanism and sanitization:\n\n```","public_affected_ranges":["<= 5.9.0"]}],"null_published_at":"2026-11-07T07:07:39.836Z","source_updated_at":"2026-05-26T19:05:11.000Z","source_disclosed_at":"2026-05-26T19:05:10.000Z","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":"2026-11-07T00:53:22.747Z"}],"next_cursor":null,"snapshot_revision":"42594"}