fix(trace-viewer): neutralize object and embed tags in snapshot renderer#40761
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pavelfeldman merged 2 commits intomicrosoft:mainfrom May 10, 2026
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Neutralize <object data> and <embed src> attributes in the snapshot renderer. Both can load arbitrary HTML in the trace viewer's origin via /sha1/ resources, bypassing the script and iframe sanitization added in microsoft#40655 and microsoft#40676. Signed-off-by: Sebastien Tardif <sebtardif@ncf.ca>
| attrName = '__playwright_' + attr.toLowerCase() + '__'; | ||
| } | ||
| if (upperName === 'OBJECT' && attr.toLowerCase() === 'data') { | ||
| // Neutralize <object data> - it can load arbitrary HTML in the trace |
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Let's drop all thees "neutralize" comments, they are noise.
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Done, dropped all the comments.
pavelfeldman
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May 10, 2026
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Test results for "MCP"2 failed 7055 passed, 1068 skipped Merge workflow run. |
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Test results for "tests 1"3 flaky41731 passed, 850 skipped Merge workflow run. |
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Summary
<object data>and<embed src>in the snapshot renderer. Both can load arbitrary HTML in the trace viewer's origin, bypassing the script and iframe sanitization added in fix(trace-viewer): sanitize snapshot renderer against XSS from crafted traces #40655 and fix(trace-viewer): strip event handlers and neutralize IFRAME srcdoc/sandbox in snapshot renderer #40676.Attack scenario
A crafted trace can include a resource containing malicious HTML/JS with content type
text/html, and a snapshot referencing it via<object data="/sha1/<sha1>" type="text/html">. The service worker serves the resource at/sha1/with the attacker-controlled content type. The<object>tag renders it in a browsing context within the trace viewer's origin, giving the attacker full JS execution. This allows exfiltrating sensitive data from the trace (API keys, cookies, auth tokens from the tested application).<embed src>has the same issue. Althoughsrcis processed byrewriteURLForCustomProtocol, relative URLs (like/sha1/...) pass through unchanged becausenew URL(relativePath)throws and the catch block returns the URL as-is.Fix
Rename
dataon<object>andsrcon<embed>to__playwright_data__/__playwright_src__, following the same pattern used for<iframe src>and<iframe srcdoc>since #40676.Origin
The iframe
srcneutralization was introduced by Simon Knott (2024-09-04). It was expanded in #40676 to coversrcdocandsandbox, but<object>and<embed>were not covered.