Content-Disposition added for @ResponseBody methods explicitly mapped to ".html" or other extensions [SPR-13629]

[spring-projects-issues]

Rossen Stoyanchev opened SPR-13629 and commented

The fix to protect against RFD exploits (#18124) introduced a "Content-Disposition:attachment;filename=f.txt" response header for @ResponseBody methods where the URL appears to have an extension that is neither whitelisted by default nor explicitly registered by the application.

By default ".html" is not whitelisted since a controller method returning String can be rendered as any requested content type (since StringHttpMessageConverter accepts "*/*") and in the case of HTML that can lead to XSS and RFD attacks.

However as commented under Spring Boot #4220 we should consider ways to make it straight-forward to render HTML via @ResponseBody when that is the actual intent.

spring-projects/spring-boot#4220 (comment)

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Affects: 3.2.15, 4.1.8, 4.2.2

Issue Links:

• Behavior change to Content-Disposition on @RequestMapping endpoint [SPR-13645] #18222 Behavior change to Content-Disposition on @RequestMapping endpoint ("is duplicated by")
• Protect against RFD exploits [SPR-13548] #18124 Protect against RFD exploits
• Content-Disposition header causes download in browser for Spring Boot Actuator endpoints [SPR-13587] #18164 Content-Disposition header causes download in browser for Spring Boot Actuator endpoints

Referenced from: commits f2e4da3, 237439e, d500d52, e190f26, 6a9329c, bdb71e9

Backported to: 4.1.9, 3.2.16

[spring-projects-issues]

Rossen Stoyanchev commented

There is some very good feedback under the Boot ticket 4220.

While it's reasonable not to whitelist "html" by default (thus exposing controller methods returning String) we can also eliminate the need to explicitly register ".html" for content negotiation purposes. For example if the mapping includes ".html" or has a produces condition we shouldn't need anything further.

[spring-projects-issues]

Rossen Stoyanchev commented

Re-opening and updating the title to a reflect a more general aim to fix this for any extension that's explicitly present in the mapping (not only ".html").

[spring-projects-issues]

Rossen Stoyanchev commented

This now works so that any extension explicitly present in a request mapping is okay. Furthermore, specifically for ".html" in the URL we do allow suffix pattern matching if the method explicitly states that it produces "text/html".

[spring-projects-issues]

blop commented

Can we disable this behaviour somehow ?
I'm not sure it's a good idea to assume every that HTTP client is be a web browser with all the security issues involved with it.