CVE-2021-29991 Other in Firefox

What is CVE-2021-29991?

CVE-2021-29991 is a high-severity vulnerability in Mozilla Firefox, published on 3 Nov 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

Official 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.

Weakness: CWE-444

Which versions are affected by CVE-2021-29991?

It affects 2 products.

Products include Mozilla Firefox, Mozilla Thunderbird.

How do I fix CVE-2021-29991?

Upgrade to a fixed version.

Is CVE-2021-29991 being exploited?

There is no known exploitation of CVE-2021-29991 in the wild and no public exploit code.

Other vulnerabilities in Mozilla Firefox

• CVE-2019-11708 Mozilla Firefox and Thunderbird Sandbox Escape Exploited Critical 10.0
• CVE-2010-3765 Mozilla Multiple Products Remote Code Execution Exploited Critical 9.8
• CVE-2022-26486 Mozilla Firefox Use-After-Free Exploited Critical 9.6
• CVE-2022-26485 Mozilla Firefox Use-After-Free Exploited High 8.8
• CVE-2019-11707 Mozilla Firefox and Thunderbird Type Confusion Exploited High 8.8

All Mozilla Firefox vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-8p2q-73gc-fxq5, UBUNTU-CVE-2021-29991, USN-5047-1.