#VU55935 HTTP response splitting in Mozilla Firefox and Mozilla Thunderbird


Published: 2021-08-18

Vulnerability identifier: #VU55935

Vulnerability risk: Medium

CVSSv3.1: 5.7 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-29991

CWE-ID: CWE-113

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Mozilla Firefox
Client/Desktop applications / Web browsers
Mozilla Thunderbird
Client/Desktop applications / Messaging software

Vendor: Mozilla

Description

The vulnerability allows a remote attacker to perform HTTP splitting attacks.

The vulnerability exists due to the affected software incorrectly accepts a newline in a HTTP/3 header, interpretting it as two separate headers. A remote attacker can perform a header splitting attack against servers using HTTP/3.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Mozilla Firefox: 80.0 - 91.0

Mozilla Thunderbird: 91.0


External links
http://www.mozilla.org/en-US/security/advisories/mfsa2021-37/


Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.


Latest bulletins with this vulnerability