CVE-2021-29976 Memory corruption in Firefox

What is CVE-2021-29976?

CVE-2021-29976 is a high-severity memory corruption vulnerability in Mozilla Firefox, published on 5 Aug 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

Mozilla developers reported memory safety bugs present in code shared between Firefox and Thunderbird. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability affects Thunderbird < 78.12, Firefox ESR < 78.12, and Firefox < 90.

Weakness: CWE-787

Which versions are affected by CVE-2021-29976?

It affects 3 products.

Products include Mozilla Firefox, Mozilla Firefox Esr, Mozilla Thunderbird.

How do I fix CVE-2021-29976?

Upgrade to a fixed version.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2021-29976 being exploited?

There is no known exploitation of CVE-2021-29976 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 DEBIAN-CVE-2021-29976, GHSA-jv3x-w8ff-cj2g, UBUNTU-CVE-2021-29976.