CVE-2021-29991

HIGH

Firefox < 91.0.1 - HTTP Request Smuggling via HTTP/3 Header Newline Injection

Title source: llm
STIX 2.1

Description

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. This vulnerability affects Firefox < 91.0.1 and Thunderbird < 91.0.1.

References (2)

Core 2
Core References
Permissions Required x_refsource_misc
https://bugzilla.mozilla.org/show_bug.cgi?id=1724896

Scores

CVSS v3 8.1
EPSS 0.0089
EPSS Percentile 54.3%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N

Details

CWE
CWE-444
Status published
Products (2)
mozilla/firefox < 91.0.1
mozilla/thunderbird < 91.0.1
Published Nov 03, 2021
Tracked Since Feb 18, 2026