Bug 1995267 (CVE-2021-29991)

Summary: CVE-2021-29991 Mozilla: Header Splitting possible with HTTP/3 Responses
Product: [Other] Security Response Reporter: Pedro Sampaio <psampaio>
Component: vulnerabilityAssignee: Nobody <nobody>
Status: NEW --- QA Contact:
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Priority: high    
Version: unspecifiedCC: erack, jhorak, nobody, stransky, tpopela
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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The Mozilla Foundation Security Advisory describes this flaw as: Firefox incorrectly accepted a newline in a HTTP/3 header, interpretting it as two separate headers. This allowed for a header splitting attack against servers using HTTP/3.
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Bug Depends On: 1996585, 1996586, 1996588, 1996589, 1996590, 1996591, 1996592, 1996593, 1996594, 1996595, 1996596, 1996597    
Bug Blocks: 1995268    

Description Pedro Sampaio 2021-08-18 17:24:29 UTC
Firefox incorrectly accepted a newline in a HTTP/3 header, interpreting it as two separate headers. This allowed for a header splitting attack against servers using HTTP/3.

References:

https://www.mozilla.org/en-US/security/advisories/mfsa2021-37/