WebSub: Reflected script execution through intent-verification challenges
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||
|---|---|---|---|---|---|---|---|---|---|
| w3c | websub | affected |
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No data.
No data.
| Vendor | Product | Versions | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| W3c | Websub |
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No CVSS v4.0
No CVSS v3.0
No CVSS v2
This CVE is not in the KEV list.
Exploit prediction score: < 1% (0.233% probability within 30 days)
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
W3c
W3c websub |
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| Vendors & Products |
W3c
W3c websub |
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
ssvc
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| Type | Values Removed | Values Added |
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| Description | WebSub is a W3C recommendation produced by the Social Web Working Group. In recommendation REC-websub-20180123, the intent-verification protocol requires a subscriber to echo the `hub.challenge` value, also exposed as `hub_challenge` by some frameworks, but does not require safe response media typing or disabled MIME sniffing. An attacker can initiate a subscription to obtain a callback URL and redirect a victim browser to a crafted verification request containing HTML or JavaScript. Subscribers that return the challenge as `text/html` can execute the reflected content in the subscriber origin, using a victim's existing session to read private data or perform actions, exposing `localStorage` or `sessionStorage` and browser permissions granted to that origin. An alternative uses the verification response as an attacker-controlled same-origin script resource to bypass `script-src 'self'`; this can remain possible with `application/octet-stream` when MIME sniffing is allowed. Safe media typing and `X-Content-Type-Options: nosniff` are both needed to address the described scenarios. WebSub Rocks demonstrated reflection, but the advisory does not establish practical impact on that demonstration site. | |
| Title | WebSub: Reflected script execution through intent-verification challenges | |
| Weaknesses | CWE-79 | |
| References |
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| Metrics |
cvssV3_1
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